Wiley: International Journal for Numerical and Analytical Methods in Geomechanics: Table of Contents

General Variational Formulation of Axisymmetric Capillary Bridges: Modeling Contact Angle Hysteresis and Capillary Forces

Olivier Millet, Antoine Moreau, Antoine Logerot, Marc Médale — Mon, 08 Jun 2026 08:26:48 -0700

ABSTRACT

This work presents a general framework for deriving the Young–Laplace equation and the Young's equations for an axisymmetric capillary bridge between two parallel plates by minimizing the system's total energy. These Young's equations naturally emerge as boundary conditions associated with the Young–Laplace equation. An additional term accounting for the contact line energy is incorporated into the total energy to model the contact angle hysteresis observed experimentally (advancing and receding contact angles). Minimization of this augmented total energy leads to generalized Young's equations. The proposed approach also provides a consistent and general definition of the corresponding capillary forces.

Nordgren PINNs to VQE: Advancing Hydraulic Fracturing Simulations in Shale Reservoirs

Fri, 05 Jun 2026 07:15:26 -0700

ABSTRACT

This study advances hydraulic fracturing simulations in shale reservoirs using two computational paradigms, Physics-Informed Neural Networks (PINNs) and the Variational Quantum Eigensolver (VQE). PINNs were employed to solve Nordgren's equation, which governs fracture width evolution, by embedding physical laws into the neural network architecture. Using TensorFlow on Google Colab, the PINN training process incorporated Adam, L-BFGS, and Newton-CG optimizers, reaching a final loss of 1.23×10−9$1.23\times 10^{-9}$ for a representative benchmark case (e.g., fluid viscosity μ$\mu$ = 8.0 Pa·s$\rm{Pa}\cdot\rm{s}$, fracture height H$H$ = 2.0 m, and leak-off coefficient CL$C_L$ = 1.0); these parameters are used for comparison and are not tied to a specific field dataset. However, this approach demands computational resources, with training times exceeding 1454 s and memory usage of 1136 MB. Conversely, the VQE framework leveraged Qiskit on Qbraid to optimize the Hamiltonian representing the fracture system in practice. With qubit-based ansatz circuits and classical optimizers (SPSA, COBYLA, and L-BFGS), VQE achieves energy minimization, converging to -0.583+0j in under 2 s with low memory requirements. Spatiotemporal fracture width predictions from VQE align with trends but exhibit slight oscillations due to quantum noise. This comparative study highlights a trade-off: PINNs show stronger physics-consistent accuracy in the tested cases, while VQE provides lower runtime and memory use. These results suggest that combining PINN accuracy with VQE speed may be useful for decision-support workflows in hydraulic fracturing. Future research will explore integrating these paradigms for scalable, high-fidelity simulations across complex geological settings.

Anisotropic Initial Damage and Its Effect on Tensile Response of Plain Concrete

A. Fau, A. A. Basmaji, U. Nackenhorst, R. Desmorat — Thu, 04 Jun 2026 03:24:44 -0700

ABSTRACT

Damage is often described as isotropic, implying that a scalar value describes its initial state. However, the prior micro-cracking pattern at points of an existing building, that is, the initial damage, may be oriented by a preload. The degradation of the Volume Element due to oriented preloads shall be described as anisotropic and represented by a tensorial variable. While this damage variable could be a fourth-order tensor, a second-order tensor is chosen as a pertinent approximation, simplifying computations of the model response. This work aims to account for non-zero anisotropic initial damage states, and analyze their effect on plain concrete tensile response. The anisotropic initial damage is parameterized in two steps: (i) a description of the tensor in its principal basis and (ii) the orientation of its principal basis. Continuum Damage Mechanics simulations are performed for given initial damage tensors. The effect of initial damage on the tensile response of concrete is then quantified on the peak stress and various post-peak quantities of interest, such as damage invariants (hydrostatic and von Mises equivalent damage) and relative distance to isotropy of the effective compliance tensor. How the anisotropy and orientation of the principal basis of the initial damage tensor affect the mechanical response is analyzed and discussed, based on the two-step parameterization. This work highlights that the observed discrepancy of tensile responses of concrete or mortar may be attributed to anisotropy and orientation of initial damage states. In particular, orientation is found to be most influential for uniaxial anisotropic initial damage.

The Behavior of Compression‐Hardening at Crack Closure Stage Explored by Stiffness Rising Model (SRCM) Under Triaxial Compression: A DEM Study

Thu, 04 Jun 2026 01:25:52 -0700

ABSTRACT

Native microcracks significantly influence the strength and deformation characteristics during the crack closure stage under triaxial compression. This study proposes a stiffness rising contact model (SRCM) with clear physical significance to describe the stiffness evolution at this stage, implemented within a 2D DEM framework. A series of biaxial rock numerical simulations is successfully conducted using sample dimensions consistent with the ISRM standard. Additionally, a three-step application framework is presented in detail. First, based on triaxial experimental data, the relationship between the secant shear modulus (Gsec${{G}_{sec}}$) and deviatoric stress (q$q$) during the crack closure phase is accurately described by a power function, with the crack closure threshold serving as the termination point for stiffness variation. Gsec${{G}_{sec}}$ and q are further characterized through the SRm$S{{R}_m}$ parameter in the SRCM and the average normal force (⟨fn⟩$ \langle {{f}_n} \rangle $) in particle agglomerates. The numerical simulation results for both stiffness rising and constant stiffness behaviors are compared with experimental data from red sandstone. The simulations demonstrate that by defining the crack closure stress (σcc${{\sigma }_{cc}}$), the crack closure behavior of red sandstone can be effectively captured. The stress-strain response predicted by the SRCM closely aligns with the experimental data, with significantly smaller errors compared to the constant stiffness model, thereby validating the proposed method.

An Analytical Solution for Groundwater Flow Induced by Localized Leakage in a Tunnel

Tue, 02 Jun 2026 03:42:05 -0700

ABSTRACT

Tunnel engineering often faces water leakage challenges. However, theoretical studies examining the effect of a localized leakage defect on tunnel structures remain scarce. This study systematically investigates the groundwater flow field in deeply buried tunnels, with a focus on a localized leakage defect, and develops corresponding analytical solutions. By employing the image method and seepage mechanics, the semi-infinite seepage field is transformed into an infinite field containing the actual tunnel and its virtual image. For unlined tunnels, the solution reduces to the classical forms proposed by Goodman and Harr, confirming its theoretical soundness. Furthermore, the proposed solutions are rigorously verified against both 2D and 3D numerical simulations, demonstrating the accuracy of the analytical derivation and the applicability of the equivalent diameter method for spatial leakage analysis. In addition, a comprehensive parameter analysis is conducted to explore the influence of the permeability coefficient, crack width, burial depth, tunnel radius, lining thickness, and grouting ring thickness on the groundwater flow field. Finally, design recommendations for the grouting ring are provided, considering the combined effects of leakage inflow and water pressure on tunnel structures.

Random Field Model for Longitudinal Vibration Analysis of Pipe Piles in Bidirectionally Heterogeneous Soil

Yuan Tu, Chengjun Guan, Minjie Wen, Yiming Zhang, Xiaonan Ge, Jinan Jin — Tue, 02 Jun 2026 03:04:57 -0700

ABSTRACT

The inherent spatial variability of soil severely impacts the vibration of pipe piles, undermining the reliability of low-strain integrity testing. Conventional deterministic models fail to adequately capture these effects. This study proposes a novel random field model to analyze the longitudinal vibration of pipe piles in bidirectionally heterogeneous soil. The model integrates the radial and vertical variability of the external soil with the vertical variability and mass inertial effects of the soil plug. Parametric analysis reveals that the degree of the soil variability in shear wave velocity has a dual impact on the vibration characteristics. For short piles, this variability acts as detrimental interference, increasing the failure probability of pile length detection. Conversely, the effect differs for long piles, which are often characterized by weak signals. For these piles, a moderate degree of soil variability can actually enhance the pile-toe reflection, serving as a “natural signal enhancer” and significantly reducing the failure probability. Furthermore, a strong correlation was identified between construction disturbance and soil variability. The randomness of the external soil is the dominant factor determining failure modes, rather than the randomness of the soil plug. This research establishes a robust probabilistic framework for reinterpreting signals from low-strain pile testing in variable soils, providing valuable theoretical guidance for improving the accuracy of pile integrity assessments.

Polymaterial Lattice Discrete Particle Model for the Optimization of Lightweight Aggregate Concrete: Intragranular Fracture and Compression Behavior

Sat, 30 May 2026 03:25:58 -0700

ABSTRACT

Lightweight aggregate concrete (LWAC) offers clear advantages for sustainable construction, including reduced density and improved thermal insulation. However, its mechanical and fracture behavior is difficult to characterize due to the heterogeneity and brittle crushing of porous lightweight aggregates. This study examines the mechanical response and fracture behavior of ultra-high-performance concrete with foam glass aggregates (UHPC–FGAs) as a representative LWAC system by combining targeted experiments with mesostructure-resolved numerical simulations. Experimental investigations included single-particle crushing tests on FGAs, uniaxial compression tests on the UHPC matrix, and three-point bending (TPB) tests on the UHPC matrix. These data informed parameter identification for the Polymaterial Lattice Discrete Particle Model. Aggregate-related parameters were calibrated under joint constraints to reproduce both FGA crushing behavior and the compressive response of UHPC–FGA composites. Realistic mesostructures were generated from voxel-based microstructures produced by the Virtual Cement and Concrete Testing Laboratory and mapped into the numerical model. TPB simulations of UHPC–FGA composites were then performed to quantify fracture energy. Results show that cracking initiates within porous FGAs and propagates transgranularly into the UHPC matrix, rather than along interfaces as in normal-weight concrete. The fracture energy of UHPC–FGAs is approximately 50% lower than that of plain UHPC, reflecting limited crack deflection and bridging. Parametric analyses indicate that aggregate stiffness and tensile strength primarily govern fracture energy and post-peak ductility, while the shear-to-tensile strength ratio controls compressive strength and peak strain. The proposed experimental–numerical framework offers practical guidance for optimizing lightweight concrete systems by balancing strength and ductility.

New Stability Charts for the Quick Assessment of Soil Slope Stability

Fri, 29 May 2026 07:19:52 -0700

ABSTRACT

The assessment of slope stability is crucial for the evaluation of the landslide risks. In practice, the engineers may need to perform a quick assessment on slope stability in the field, and the stability chart would provide convenience for this purpose. The original stability number chart is a tool that can provide a quick assessment of the soil slope stability from the slope geometry and soil properties. However, the original stability number chart was proposed mainly based on the hand calculation. With the development in computation, there are much more advanced analysis methods available based on the limit equilibrium method as compared method for stability number chart. In this paper, the method of published stability number chart was reviewed, and the limitation of the original chart is highlighted. Subsequently, the factors of safety for slopes with varying slope geometry and soil properties were evaluated using the limit equilibrium software Slope/W. The discrepancies between the results from Slope/W and the original stability number chart were discussed and then validated by comparing with the published cases. It was observed that the published chart only considered slip surface and factor of safety for certain conditions, while the results from Slope/W indicated three types of slip surface and a comprehensive factor of safety. In addition, the former method required iterative trial calculations while the latter method only required searching for charts of the corresponding parameters. Consequently, the new stability charts were proposed from the results of Slope/W for quick assessment of the soil slope stability.

Enhancing Rock Strength Prediction and Features Selection by Coupling Well Log Data and Deep Learning Approaches in Reservoir Geomechanics

Mohammad Islam Miah, Md. Shakil Rahaman, Travis Wiens — Thu, 28 May 2026 02:29:51 -0700

ABSTRACT

Accurate rock strength parameters play a vital role in petroleum and mining operations for sustainable drilling activities, and wellbore stability analysis. This study investigates the applicability of deep learning techniques for assessing data-driven models, and to conduct parametric sensitivity examination for feature attributes ranking to predict compressive strength (UCS) of clastic sedimentary rocks. The predictor variables of well logs data such as formation density, gamma-ray (GR), compressional acoustic wave velocity (V_p), and share wave velocity (V_s) are utilized. The convolutional neural network (CNN), multi-layer perception-based neural network (MLPNN), and transformer-based predictive models’ outcomes are assessed for checking the models’ reliability, robustness and feature selections using statistical performance indices. The Taylor diagram also employed to examine the importance of the variations in model outcomes. The variables’ dimensionality reduction and features importance are measured applying Shapley additive explanation (SHAP), and three filter approaches. Based on the findings, the transformer model outperformed the MLPNN and CNN models, with high accuracy (correlation coefficient of 0.99) and root mean square error of 1.3 MPa. For instance, GR and V_p are the most significant predictor variables to obtain UCS for the studied field, compared and verified by SHAP and filter methods of mutual information, Fisher score, and Chi-Square test. In the light of these findings, it is revealed that these novel deep learning approaches provide valuable insights into model development and feature attributes selection to estimate rock strength parameters and optimize drilling parameters for wellbore stability analysis to reduce operational risk in petroleum and minerals exploration.

Semi‐Analytical Solution of Time‐Harmonic Soil–Pile Interaction Using Love Numbers in Transversely Isotropic and Layered Half‐Spaces

Wed, 20 May 2026 01:56:22 -0700

ABSTRACT

An efficient semi-analytical approach based on the Fourier–Bessel series (FBS) system of vector functions and the stiffness matrix method is proposed to study the dynamic response of axially loaded piles embedded in transversely isotropic (TI) layered soil. The method utilizes a robust free-field matrix formulation of layered soil that integrates with the pile matrix, enabling efficient computation of expansion coefficients, termed as Love numbers. These coefficients need to be computed only once for multilayered soil. They are then stored and reused to quickly obtain responses at multiple field points using FBS synthesis, avoiding the computational complexity of the Hankel integral transform. The proposed formulation is validated against various existing solutions, demonstrating excellent agreement. Furthermore, the effects of compressibility, slenderness, pile spacing, soil anisotropy, layering, and frequency-dependent loading on the pile–soil interaction are investigated, offering practical insights for improved and reliable pile design.

Development of the Nonlocal Deformation Constitutive Model and Its Application in Exploring the Inclination Effect on Localized Shear Deformation of Rock in FLAC3D

Lanxin Liu, Binyu Luo, Yicheng Ye, Tengda Huang, Xiaoyun Liu, Pengcheng Li — Wed, 20 May 2026 01:32:45 -0700

ABSTRACT

Mastering rock local deformation and failure characteristics under different inclined loading angles is crucial for rock mass engineering stability, like that of inclined pillars. To address the inability of traditional local models to accurately describe rock's nonlocal deformation and strain localization under compression-shear loads, this study conducts systematic innovative research. First, after briefly reviewing the core of nonlocal theory, the Mohr-Coulomb criterion is modified by innovatively introducing a softening modulus and nonlocal internal variables, yielding an improved nonlocal constitutive model for rock deformation. Leveraging FLAC3D's large-deformation analysis capability and open secondary development interface, an innovative and practical “double-cycle” computational framework is proposed: the outer cycle processes nonlocal zone information and updates nonlocal internal variables in real time, while the inner cycle performs stress iterations via constitutive equations. This overcomes bottlenecks like inefficient variable updates and insufficient coupling in traditional nonlocal numerical implementations, enabling efficient and stable computation. Through combined experimentation and numerical simulation, the influence of loading inclination on rock's local deformation is explored, revealing compression-shear deformation characteristics and proposing a rock instability prediction method. Results show the “double-cycle” model effectively handles nonlocal variable assignment and update. The nonlocal constitutive model captures rock nonlocal deformation well, and the second-order difference in plastic deformation element number can predict rock peak stress. At a certain dip angle, local deformation zone formation lags peak stress; as the dip angle rises, rock peak strength drops and fracture angle increases. These findings offer a theoretical basis for inclined rock strata stability analysis in engineering.

Analytical Solutions for Stability of Geosynthetic‐Encased Stone Column‐Supported Geosynthetic‐Reinforced Embankment

Xiaocong Cai, Ling Zhang, Zijian Yang — Tue, 19 May 2026 22:00:19 -0700

ABSTRACT

A novel three-wedge limit equilibrium framework is developed to address the stability assessment of embankments reinforced with geosynthetic-encased stone columns (GESCs) combined with basal geosynthetics. The proposed model comprises five slip surfaces and is capable of accommodating a wide range of conditions, including variable geometry, strength parameters, vertical and horizontal reinforcement, surcharge, pore water pressure, and seismic coefficients. A global factor of safety (FS) is applied consistently across all potential failure surfaces and reinforcement members, and is determined analytically by solving the sixth-order polynomial equation. This analytical solution provides a compact form method for FS calculation. Validation against the numerical modeling and other analytical methods demonstrates a strong concordance, confirming the reliability and accuracy of the proposed method in predicting system stability and failure mechanisms. The parametric study is conducted to further guarantee the rationality of the analytical method. The parametric analysis reveals that the shear strength of the in-situ soft soil and the horizontal seismic coefficient are the dominant factors controlling system stability, surpassing the influence of reinforcement strength and embankment geometry in many scenarios.

A Limit Analysis Model for Active Earth Pressure in Unsaturated Soils Considering Capillary‐Adsorptive Stress and Composite Tensile–Shear Failure Mechanism

Linghao Qi, Yajun Zhang, Jingshu Xu, Wenpei Wang, Mi Zhao, Xiuli Du — Tue, 19 May 2026 05:46:50 -0700

ABSTRACT

Saturated-based approaches relying on shear-failure assumptions inadequately describe rainfall-induced active earth pressure in unsaturated soils. This study presents a three-dimensional (3D) upper-bound analytical framework for active earth pressure in unsaturated soils by coupling a unified suction-stress formulation with a composite tensile–shear failure mechanism. Both adsorptive and capillary contributions to suction stress are explicitly incorporated, and hydraulic hysteresis effects are considered through differentiated wetting and drying strength evolution. A two-segment rotational failure mechanism, consisting of an upper tensile-dominated zone and a lower shear-dominated zone, is formulated while maintaining velocity continuity along the entire failure surface. Soil–wall roughness is explicitly included to account for interface friction effects. Closed-form solutions for the active earth pressure coefficient are derived. A parametric analysis examines the influences of suction-stress parameters, rainfall intensities and patterns, wall roughness, and 3D geometry. The results demonstrate distinct time-dependent earth pressure responses governed by adsorption–capillarity partitioning, hysteresis, and interface conditions. This research provides a theoretical framework for evaluating active earth pressure on retaining structures under unsaturated states under rainfall infiltration.

Effect of Strength Spatial Variability on the Probabilistic Post‐Landslide Behavior of Heterogeneous Slopes Under Rainfall

Chao Su, Ailan Che, Hanxu Zhou, Ganglie Yuan, Jifang Zhou — Tue, 19 May 2026 03:21:25 -0700

ABSTRACT

The strength spatial variability and the complex hydro-mechanical interactions render the quantitative evaluation of rainfall-induced landslides a persistent challenge. The probabilistic analysis methods face critical limitations: the traditional small-deformation numerical methods cannot capture post-landslide consequences, while direct large-deformation analysis is computationally prohibitive. Therefore, this study develops an integrated random finite element method—material point method (RFEM-MPM) approach to analyze the entire failure process, with particular emphasis on the post-landslide stage. The approach builds upon a sequential FEM-MPM coupling scheme, extended through a secondary development that enables the import and storage of spatially variable strength properties directly at the material point level. This allows for the integration of random field (RF) theory into the MPM for probabilistic analysis. The cohesion and internal friction angle are modeled as a bivariate cross-correlated RF. Monte Carlo simulations (MCS) are performed considering the strain-softening characteristics of the soil. The failure criterion is identified through the factor of safety (FoS), combining FEM's computational efficiency for pre-landslide seepage-stability analysis with MPM's large-deformation capabilities through equivalent state mapping. The post-landslide behavior is quantitatively assessed using four large-deformation parameters: sliding volume, runout distance, retrogressive distance, and sliding depth. The results indicate that the approach achieves a 95.1% computational reduction compared to the random material point method (RMPM). The strength spatial variability significantly affects the slope stability, large-deformation characteristics and failure modes. Increased variability in strength parameters leads to wider, right-skewed distributions of runout distance and sliding volume, increasing the probability of extreme failure events.

Longitudinal Seismic Behavior of Cracked Tunnels Crossing Faults: Insights From a Fracture‐Aware Modeling Approach

Xianwang Liu, Chao Liu, Jie Cui, Hai Liu, Junzuo He, Pei Wang — Tue, 19 May 2026 03:14:50 -0700

ABSTRACT

Tunnel linings crossing active fault zones are critical vulnerabilities in underground infrastructure due to long-term seismic and tectonic stresses. Focusing on cast-in-place linings, this study develops an analytical framework for evaluating the longitudinal seismic response of cracked tunnels traversing fault fracture zones. The lining is modeled as a multi-cracked Euler-Bernoulli beam supported on three distinct Pasternak elastic foundations. A generalized solution for bending deformation under arbitrary crack configurations is derived using Laplace transforms, which is then validated through benchmark cases and 3D extended finite element (XFEM) simulations incorporating concrete damage plasticity. Parametric studies reveal that crack-induced stiffness reduction creates localized deformation singularities, where deeper cracks amplify a stress-relief effect, suggesting that engineered settlement joints could strategically mitigate dynamic loads. Paradoxically, increasing lining bending stiffness elevates internal force magnitudes by up to 31.3%, challenging conventional reinforcement strategies. Furthermore, while wider fault zones monotonically increase deformation and bending moments, they induce a non-monotonic shear response that peaks at the fault-hanging wall interface. The axial influence range of seismic effects also expands with fault width. This framework provides a physics-informed tool for optimizing crack-tolerant designs in fault-crossing tunnels, effectively balancing deformation accommodation and load redistribution under seismic excitation.

Implicit Stress Integration of Highly Nonlinear Sand Models With Line Search Method and Complex‐Step Jacobian Evaluation

Yaning Zhang, Zhiwei Gao, Dechun Lu, Xin Zhou, Fengwen Lai, Xiuli Du — Mon, 18 May 2026 08:14:57 -0700

ABSTRACT

Although bounding-surface plasticity models have been extensively studied, robust fully implicit implementations for SANISAND-type models, especially in boundary-value analysis, remain limited because of severe nonlinearities and the difficulty of accurate Jacobian evaluation. To address these challenges, this study develops a robust fully implicit stress integration framework for highly nonlinear soil models by combining a line search-enhanced Newton-Raphson method (LSNRM) with a complex-step differentiation method (CSDM), and demonstrates it through the implementation of the SANISAND-04 model in ABAQUS/Standard. This constitutive model is well known for its ability to capture the complex behavior of sand, which involves strong nonlinearities stemming from state-dependent dilatancy, kinematic hardening, fabric tensor effects, and stress reversals. The implementation is thoroughly evaluated in terms of correctness, accuracy, and quadratic convergence at both the Gauss point and global structural levels. Finally, the proposed framework is further validated through a benchmark simulation of strip footing bearing capacity, demonstrating its applicability to a representative nonlinear boundary-value problem.

A Modified Inverse Analysis Method for Soil Parameters Considering the Spatial Structure of Soil Layers

Mon, 18 May 2026 06:36:34 -0700

ABSTRACT

When evaluating the impact of foundation pit excavation on adjacent existing metro structures through numerical simulation, it is essential to adopt a reasonable constitutive model and parameters. This study proposes an innovative inverse analysis method for soil parameters that considers the spatial structure of soil layers. Unlike traditional inverse analysis methods, this approach reconstructs the target parameters based on the spatial distribution characteristics of the soil layers, transforming discrete and independent parameters into a sequential structure (sequence). Using the reconstructed sequence as input and structural deformation as output, a surrogate model is established and combined with an optimization algorithm for inverse analysis of soil parameters. The proposed method was validated through numerical approaches, and the results demonstrate that, compared to conventional methods, the proposed method reduces the mean absolute error (MAE) of surrogate model predictions for structural deformations by up to 29.7% and decreases the MAE of numerical simulation results based on inversely analyzed parameters by up to 48.9%. Subsequently, the method was applied to an actual engineering project to verify the reliability of the soil parameters it provides. Finally, SHapley Additive exPlanations (SHAP) analysis was conducted to explore the interpretability of the machine learning model. The results indicate that the soil parameter G0ref$G_0^{ref}$ not only contributes the most to the structural deformation but also interact strongly with other parameters. Furthermore, for the soil layers, the contribution of deeper soil layers to structural deformation is generally higher than that of the upper layers.

Conceptual Investigation of Thermoelectric Linings of Tunnels in High‐Geothermal Environments

Mon, 18 May 2026 01:14:32 -0700

ABSTRACT

High-geothermal environments present significant challenges for tunnel construction and operation while simultaneously offering promising opportunities for renewable energy utilization. In response, this study proposes a novel high-geothermal tunnel thermoelectric generator (HGT-TEG) system, designed to convert geothermal heat into electrical energy. A numerical model was developed to investigate the heat-transfer characteristics and power generation performance of the system. The model was validated through comparison with both on-site measurements and laboratory experiments. A parametric analysis revealed that the thickness of the thermal insulation layer and the spacing of thermoelectric modules (TEMs) are key factors, affecting the power output. Furthermore, the integration of thermal conductive layers significantly enhanced the effective temperature gradients across TEMs, thereby improving the overall system performance. Under geothermal conditions with a surrounding rock temperature around 92°C, an HGT-TEG system, featuring 30 cm spacing between TEMs in a 1 km tunnel segment (8 m wide, 10 m high), generated an estimated 4867 kWh of electricity, annually. The proposed HGT-TEG system represents a viable and sustainable solution for geothermal energy harvesting, contributing to the resilience and sustainability of tunnel infrastructure in geothermally active regions

Earth Pressures on Underground Structures in Long Vertical Trenches With Heterogeneous and Nonlinear Soil Backfills Using a Slice‐Based Numerical Approach

R. Ganesh — Fri, 15 May 2026 04:13:34 -0700

ABSTRACT

The earth pressures on underground structures in trenches are typically evaluated using the conventional Mohr-Coulomb (MC) yield criterion under the assumption of homogeneous soil backfills. However, most geomaterials are inherently heterogeneous and exhibit nonlinear shear strength characteristics. In this research, a novel slice-based numerical solution procedure based on the limit equilibrium method of horizontal slices is developed to evaluate the earth pressure distribution in long vertical trenches backfilled with heterogeneous soils exhibiting nonlinear shear strength. The analysis is carried out under plane strain conditions and employs the nonlinear power-law (PL) yield criterion together with linearly varying soil parameters to account for the nonlinear and heterogeneous characteristics of the soil backfill. The variations of vertical earth pressure (σv${{\sigma }_{\mathrm{v}}}$) with depth (z$z$) below the ground surface for homogeneous clay and sand trench backfills, evaluated using both the MC and PL yield criteria, reveal the significance of shear strength nonlinearity. A detailed parametric investigation is further conducted to examine the effects of different parameters on the variation of the σv−z${{\sigma }_v} - z$ curves. The computations demonstrate that the combined effects of soil nonlinearity, heterogeneity, and arching significantly affect both the magnitude and distribution of earth pressures within the trench. Moreover, the proposed procedure yields results that show excellent agreement with those reported in the existing literature based on the MC yield criterion.

A Coupled Extended Finite Element–Cohesive Zone Model for Hydraulic Fracture Propagation Under Poroelastic Effects Across Different Propagation Regimes

Ran Tao, Juliana Y. Leung, Samer Adeeb — Wed, 13 May 2026 07:52:38 -0700

ABSTRACT

Numerical simulation of hydraulic fracturing remains challenging due to the strong coupling between geomechanics and fluid flow when modelling multiple physical mechanisms of rock deformation, fracture evolution and fluid leak-off. This study develops a coupled hydraulic fracture propagation framework that combines the extended finite element method with a cohesive zone model (XFEM–CZM) in Abaqus. The XFEM–CZM model is subjected to a systematic comparative analysis with established numerical approaches, specifically the finite element method with a cohesive zone model (FEM–CZM) and the finite element method coupled with the displacement discontinuity method (FEM–DDM). Predictions of aperture, length, and net pressure are validated against in four limiting regimes: toughness–storage, toughness–leak-off, viscosity–storage and viscosity–leak-off. Several cases vary isotropic and anisotropic permeability, leak-off, viscosity, and mesh size to investigate poroelastic effects on fracture propagation and to enable direct comparison with previous studies. Finally, a sensitivity analysis is conducted on key XFEM parameters, including tensile strength, fracture energy under field-relevant toughness–leak-off conditions. Results show close agreement where fluid storage and viscosity dominate; under viscosity–leak-off conditions, XFEM–CZM aligns more closely with numerical solutions than with analytical solutions. Sensitivity analyses reveal the effects of key parameters, including tensile strength, fracture energy, and initial crack length, on fracture growth: tensile strength mainly governs net pressure and aperture; fracture energy impacts fracture length and propagation resistance; and initial crack length primarily affects early-time pressure response. This study simulates fractures across diverse regimes and provides guidance for parameter calibration, improved fracture characterization and design optimization in complex formations.

Capturing Complex Rate‐Dependent Behaviors of Saturated Clays: A Fractional Consistency Kinematic Hardening Viscoplastic Approach

Wei Cheng, Zhen‐Yu Yin — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Saturated high plasticity clays show complex nonlinear, rate-dependent, and hysteresis behaviors under non-monotonic stress paths, requiring advanced mathematical constitutive equations for accurate description. Taking into account the inherent advantages of kinematic hardening mechanisms in simulating complex stress histories, this paper presents a novel fractional order kinematic hardening viscoplastic model for describing complex rate-dependent features of saturated high plasticity clays: first, the modified isotach viscosity is extended into general loading conditions to consider both loading and unloading rate effects; second, a combined rate-dependent isotropic-rotational-kinematic hardening law is built through current and conjugate stress points res the non-intersection of two surfaces and smooth transition; third, a stress-fractional operator is defined to represent the non-orthogonal plastic flow direction in the proposed model; fourth, based on the consistency condition on the bubble surface, the increment form of stress-strain-strain rate relationship can be formulated and implemented into a finite element code. Parametric analyses are then adopted to demonstrate the model's capabilities under different loading paths. Finally, three different saturated clays, namely natural Boom clay, Hong Kong marine deposits, and an Earth dam core compacted clay, are employed to validate the model's effectiveness and performance via various rate-dependent non-monotonic element test results.

Molecular Insights Into the Water Freezing on Kaolinite Surfaces: The Key Role of Surface Properties

Yijie Wang, Zhen‐Yu Yin, Pierre‐Yves Hicher — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Unfrozen water content is a key factor governing the physical properties of frozen soils, and variations in mineral surface properties play a critical role in determining this content. However, the fundamental physical mechanisms of how different mineral surfaces affect soil water freezing remain poorly understood. This study employs the molecular dynamics method to investigate the influence of mineral surface on soil water freezing, taking kaolinite as an example. By constructing atomic models of kaolinite, liquid water, and an initial ice nucleus and simulating the cooling process, the temperature dependence of unfrozen water on two different surfaces of kaolinite is obtained and compared with freezing simulation data on mica. Results show that the unfrozen water film thickness decreases in the order: kaolinite alumina surface (Al-S) > mica surface (Mica-S) > kaolinite silica surface (Si-S). By employing two order parameters and analyzing hydrogen bonds (H-bonds), the study reveals that surface hydroxyl groups on Al-S promote strong water molecular ordering and extensive H-bonds, conferring superior antifreeze properties. In contrast, the Si-S exhibits limited capacity for H-bonds formation, resulting in low water molecular ordering and poor antifreeze performance. The surface cations on Mica-S increase the probability of H-bonds formation between water molecules and the mineral surface, consequently rendering its surface water more ordered than that on the Si-S and improving its antifreeze capability. This work provides atomic scale insights into soil water freezing mechanisms, aiding the interpretation of soil freezing behaviors.

Analytical Solution for a Shallow Lined Circular Tunnel Based on the Generalized Series Expansion (GSE) Method

Jian‐Fei Lu, Kang‐Qi Sun — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Due to the presence of the tunnel lining, it is difficult to develop a system of linear equations for the unknowns of a shallow lined circular tunnel (SLCT) analytically based on the conformal mapping method. Besides, the traditional complex variable based series expansion (CVSE) method is limited to the problem associated with circular boundaries. To overcome the above limitations and extend the applicability of the CVSE method, a new analytical method, that is, the generalized series expansion (GSE) method for the SLCT is developed based on complex variable method. For this purpose, two generalized series for two complex potentials of the soil are introduced. Each generalized series is composed of two parts, that is, the singular and regular parts. The singular part of each generalized series is already known and singular in the lower half-space occupied by the soil, while the regular part is unknown and analytic in the lower half-space and it can be obtained by using Cauchy's integral theorem as well as the traction free condition along the soil surface. For simplicity, the lining of the tunnel is treated as a thin cylindrical shell. With the expressions for the above generalized series and governing equation for the tunnel lining, a system of linear equations for all the unknowns of the SLCT is derived analytically, with which the response of the SLCT and soil to arbitrary external loads is obtained.

Tunnel Design in Rock Masses Under Uncertainty With Reliability Constraints and Natural Gradient Boosting‐Based Surrogates

Tran Vu‐Hoang, Tan Nguyen, Hung‐Thinh Pham‐Tran, Duy Ly‐Khuong, Tuan A. Pham — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

This study develops a reliability-based framework for predicting and optimizing tunnel stability in rock masses under surcharge loading while explicitly accounting for both aleatory and epistemic uncertainties. A unified dataset for twin circular and square tunnels is generated using Adaptive Finite Element Limit Analysis under the generalized Hoek–Brown criterion. The results demonstrate that probabilistic predictions obtained using Natural Gradient Boosting provide accurate stability estimates together with well-calibrated uncertainty bounds, consistently outperforming multiple baseline machine-learning models. Validation against more than 300 independent Optum G2 simulations confirms strong agreement with numerical benchmarks. A dedicated uncertainty decomposition analysis further shows that neglecting either input uncertainty or model uncertainty can lead to misleading and potentially unsafe reliability estimates, underscoring the necessity of joint uncertainty propagation. Overall, the proposed framework enables robust, uncertainty-aware tunnel design under reliability constraints and provides a practical decision-support tool for rock engineering applications.

Lessons Learned From Using Simple Supervised Learning Tools on Small‐Ensemble Data—Applicability to Tunnel Design and Monitoring

Lina‐María Guayacán‐Carrillo, Jean‐Michel Pereira, Jean Sulem — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Integrating interdisciplinary strategies with artificial intelligence (AI), particularly machine learning (ML), is an effective way of addressing urgent engineering challenges. Therefore, a thorough evaluation of existing methodologies is essential, taking into account their respective strengths, limitations and opportunities. This paper presents the main findings from exploratory research conducted through a variety of case studies. Based on the insights gained from these case studies, the paper critically examines three key areas of tunnelling. First, the challenges related to acquiring, generating and storing data, particularly for ML applications, are addressed. Emphasis is placed on ensuring that data are stored securely and are accessible for straightforward analysis. Second, the paper examines the application of ML to small datasets, providing insight into tunnelling requirements. It reviews ensemble methods and demonstrates their applicability using examples of small datasets. Third, the paper discusses the importance of interpretable tools in tunnel projects. Transparent and interpretable models help engineers understand model outputs, so it is important to consider this type of model wherever possible. The use of symbolic regression for estimating the long-term closure of tunnels is presented. Finally, the paper summarises the key findings and considers the future prospects of this interdisciplinary approach. The aim is to encourage further development in this area.

A Generalized Nonlinear Solution for the Transient Dynamic Response of Continuous Buried Pipelines to Underground Blast Loadings With Shear Interaction on Visco‐Elastic Foundation

Tapobrata Lodh, Kaustav Chatterjee — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Buried pipelines are highly susceptible to underground blast loads; yet, most existing analytical models overlook key factors, such as shear coupling in the supporting soil, variation in operational loads and realistic blast pressure profiles, which limit it's use in design and safety assessment. This study presents a comprehensive analytical solution for the dynamic response of buried pipelines subjected to underground blast loading, capturing realistic operational and environmental conditions. The pipeline is modelled as a continuous modified Timoshenko beam on a viscoelastic foundation with shear interaction between adjacent Winkler springs, incorporating soil overburden pressure, idealized blast loading with an exponential rise and decay, and a critical vertical loading case under pipeline running conditions. The governing equations are solved using finite Laplace transforms. Model predictions show good agreement with centrifuge model tests, three-dimensional finite element simulations, and simplified analytical results in past studies. A parametric analysis is performed to elucidate the impact of various soil, pipe, and other influential characteristics on the peak particle strain (PPS) responses of pipelines. The current framework offers a robust and computationally efficient tool for parametric evaluation, enabling optimal, scenario-specific design of buried pipelines and providing practical insights for mitigating blast-induced failures.

Analytical Modeling of Heat Transfer and Deformation Around a Circular Cavity in Elastic Ground

Arianna Lupattelli, Diana Salciarini, Alessandro F. Rotta Loria — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

The subsurface is increasingly exploited to host energy, utilities, and infrastructure systems that interact with surrounding soils and rocks through their thermal and functional operation. Prominent examples are provided by energy geostructures, district heating networks, buried power cables, steam and water pipes, and underground nuclear waste repositories. Many of these systems incorporate cylindrical cavities and operate under varying thermal conditions, thereby influencing the thermo-mechanical state of the surrounding ground. While advanced numerical simulations have significantly improved understanding of these processes, their complexity and computational cost restrict their use in engineering practice. By contrast, analytical models offer computational efficiency and theoretical rigor, but limited analytical solutions are currently available to address the analysis of cavity-type systems involving non-isothermal conditions and interconnected mechanical interactions with the ground. To address this gap, this study introduces an analytical model that extends the classical cavity expansion theory to non-isothermal conditions. The formulation integrates thermo-elastic effects under both steady-state and transient regimes, enabling the prediction of stress, strain, and displacement distributions induced by temperature variations around a cylindrical cavity. Validation against finite element simulations confirms the reliability of the proposed analytical approach across a range of subsurface conditions. The analytical model provides a practical and theoretically robust tool that overcomes the daunting resources required by multiphysical numerical modeling approaches.

Multifactor Kinematic Characteristics of Mining‐Induced Ground Fissures: Discrete Element Modeling and Prediction Model Validation

Yanjun Zhang, Yueguan Yan, Xugang Lian, Shengliang Wang, Jiayuan Kong — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

The scale characteristics of ground fissures exhibit documented variations globally, with field investigations proving inadequate to comprehensively assess the influence of mining parameters and topographical conditions. To address this limitation, large-scale numerical simulations using the discrete element method (DEM) were employed to examine the effects of depth–thickness ratio, loose layer–bedrock ratio, surface slope, and working face advancing speed on fissure characteristics. DEM validation confirms its capability to accurately replicate fissure types (tensile, step, and collapse), overlying strata failure height (3.5%, relative error [RE]), and surface subsidence evolution (2.9%, RE). Maximum fissure width, average penetration, and average advanced distance demonstrate statistically significant correlations with the examined parameters, conforming to linear, exponential, and quadratic polynomial relationships. Building upon soil mechanics principles, prediction models were derived, these yield REs of 7.1% for fissure location, 4.9% for depth, and 0.9% for average advanced angle. This study addresses a critical knowledge gap by establishing quantitative relationships between causative factors and scale characteristics while developing practical prediction methodologies. These enable engineers to optimize mining plans based on projected land damage assessment.

Reduced‐Order Modeling of the Lattice Discrete Particle Model via Proper Orthogonal Decomposition

Nima Noorollahi, Gianluca Cusatis, Alessandro Fascetti — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

The Lattice Discrete Particle Model (LDPM) provides a robust computational framework for modeling the behavior of quasi-brittle cementitious composites, excelling at simulating fracture processes, crack initiation and propagation, and material failure mechanisms at the mesoscopic scale of concrete, which schematizes the material at the level of coarse aggregate and mortar paste. However, LDPM remains computationally expensive, particularly when modeling large-scale structural elements under complex dynamic conditions. This study utilizes Proper Orthogonal Decomposition (POD) to develop a reduced-order model (ROM) for the LDPM integration solver employing the central difference scheme. A novel two-stage projection strategy is introduced, enabling direct and consistent enforcement of boundary conditions in the reduced subspace, while maintaining compatibility with the original solver. The objective is to balance accuracy and computational efficiency. In constructing the ROM, both offline and online modes are presented and discussed in detail, including the demonstration of offline ROM for mesoscale parameter calibration to enhance predictive capabilities. The proposed methodology is validated through various independent tests involving highly nonlinear behavior. The results demonstrate significant computational savings without compromising the accuracy of the numerical predictions, highlighting the potential to apply ROM techniques to the LDPM framework.

Three‐Dimensional Numerical Simulations of Large‐Diameter Slurry Shield Tunnelling: The Influence of a Dynamic Filter Cake

Yiming Zhang, Jiuhao Nie, Jiaji Yu, Qiujing Pan, Xiaoxiong Men — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

A refined simulation of slurry shield–ground interactions should consider the dynamic and heterogeneous filter cake created by slurry infiltrating and tool cutting. Previous studies often neglect the influences of dynamic and heterogeneous filter cakes on tunnelling-induced ground responses. This study utilizes slurry infiltration column tests to derive the infiltrating depth and the time-dependent permeability of the slurry-penetrated zone, which is further incorporated into a fluid–solid coupling numerical model to simulate a heterogeneous and dynamic filter cake. The proposed numerical model successfully reproduces the measured ground deformations and pore pressures in Zhuhai tunnel. It is found that the excess pore pressure rises sharply within a range of 0.5 times the tunnel diameter when a cutter disturbs and cuts through the filter cake, and then gradually dissipates as the filter cake reforms and regains its low-permeability structure. Moreover, more remaining filter cake leads to stronger pressure reduction and smaller ground deformation. A higher cutter opening ratio reduces the slurry pressure-transfer efficiency, while a more non-uniform distribution of disc cutters leads to a more rapid stabilization of the pressure-transfer process. Numerical simulations without considering fluid–solid coupling tend to overestimate the filter cake's pressure-transfer efficiency and underestimate ground deformations, yielding a maximum settlement about 15% lower than that from the coupled analysis. These results demonstrate that three-dimensional numerical simulations considering dynamic filter cakes and fluid–solid coupling enable more accurate reproduction of shield–ground interactions.

A Numerical Method Combining Cubic Interpolated Propagation and Shifted Grünwald–Letnikov for Fractional Advection–Dispersion Equations

Pedro Victor Serra Mascarenhas, André Luís Brasil Cavalcante — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Recent advances in the numerical solution of fractional partial differential equations have yielded promising results. In particular, the Shifted Grünwald–Letnikov (SGL) approach allows for a generalization of the traditional finite difference method to the context of fractional differential equations. However, when combined with the backward finite difference scheme, the SGL method for the fractional advection–dispersion equation can produce spurious results, similar to those observed in its integer-order counterpart. In this study, a novel method that combines the SGL approach with the Cubic Interpolated Propagation (CIP) denoted as CIP-SGL scheme is proposed to mitigate numerical dispersion. The accuracy and validity of the proposed method are demonstrated through computational experiments.

A Simple Approach for Circular Tunnels Excavated in Strain‐Softening and Dilatancy Rock Masses

Xiuling Wang, Yongli Xie, Jinxing Lai, Junling Qiu, Weiling Teng — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

This study proposes a simple numerical approach that incorporates rock strain-softening (SS) and dilatancy into the triple-shear-element unified strength criterion (TS-USC). A parametric analysis is conducted to elucidate rock mass responses. The results demonstrate that the intermediate principal stress (IPS) enhances rock mass stability and limits plastic zone growth. The TS-USC should be used with caution for tunnel stability evaluation because it may underestimate rock displacements. Dilatancy behaviors notably affect rock displacements but have minimal influence on plastic zone radius, radial stresses, and tangential stresses. Therefore, the dilatancy model needs to be chosen reasonably to achieve an acceptable accuracy level. Rock displacements at the excavation profile and the plastic zone radius increase approximately linearly under different SS behaviors. SS behaviors mainly affect tangential stresses; however, for a fixed SS behavior (i.e., for a given δ), radial stresses at softening-residual interface are minimally affected by supporting force. These factors deserve attentions during stability analysis and support system design.

Numerical Study on Multi‐Scale Damage of Granite Under Extreme Temperature Shock

Haodong Wang, Wenjiao Zhang, Xiaoxuan Ding, Zewen Gu, Xiangqing Kong — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Understanding the real-time thermomechanical damage of granite under extreme temperature variations is essential for the safe and efficient exploitation of hot dry rock (HDR) geothermal resources. Existing experimental studies primarily focus on macroscopic mechanical deterioration after high- or low-temperature exposure, while the microscale evolution of force chains and their dynamic coupling with macroscopic behavior remain poorly understood. Moreover, conventional DEM-based models often oversimplify rocks as homogeneous continua, neglecting mineral-scale heterogeneity and intergranular interactions. To address these gaps, a two-dimensional grain-based model (GBM) was developed to explicitly capture mineral heterogeneity and intergranular properties, enabling simulation of heating–cooling cycles and real-time damage evolution under extreme temperatures. New metrics were proposed to quantitatively evaluate force chain reorganization, load-bearing degradation, and their correlation with macroscopic strength. Simulation results reveal that although the maximum strength, average strength, and number of force chains increase with temperature, high temperatures destabilize the overall force chain network. Strong thermal shocks from high to extremely low temperatures can reduce the mechanical properties of granite, accelerate the initiation of microcracks, and promote the formation of more complex crack networks, thereby enhancing the efficiency of thermal extraction. This study provides novel insights into microscale mechanisms underlying cyclic thermomechanical damage in granite and offers theoretical guidance for the design and optimization of LN₂ fracturing strategies in HDR reservoirs.

Thermally Induced Coupled Effects on Contaminant Transport in Composite Landfill Liners: An Analytical Modeling Approach

Hao Ding, Ziheng Wang, Junbo Zhou, Haijian Xie, Chunhua Zhang — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Landfill liners serve as crucial barriers against contaminant migration. However, temperature effects can induce thermal diffusion and may cause clay liners to crack, significantly reducing containment performance. This study presents an analytical model for evaluating coupled heat and mass transport in a composite liner system. The system contains an intact geomembrane over a fractured compacted clay layer, and the model works under both steady-state and transient conditions. The model incorporates diffusion, degradation, and thermal diffusion processes within both the soil matrix and the fractures. The validity and robustness of the proposed approach were verified through comparisons with existing analytical models. Results demonstrate that high Soret coefficients accelerate contaminant transport and cause abnormal contaminant accumulation far from the source, raising pollution risks in low concentration areas. The width of the fracture plays a dominant role in the breakthrough time and steady state concentration of contaminants, while the effect of changes in fracture spacing is not significant. Temperature difference has the most significant effect on the transport of Dichlorodiphenyltrichloroethane (DDT) and is the most relatively significant factor. The proposed analytical model shows that thermal diffusion shortens the service time of barrier systems. Fractures caused by temperature gradients also reduce their service life. These effects are particularly strong in the early stage. To ensure the long-term operation of the barrier systems, it is vital to reduce the temperature difference between landfills and the external environment. It is also crucial to improve the degradation rates of contaminants and to prevent the formation of fractures.

Elastoplasticity Informed Kolmogorov–Arnold Networks Using Chebyshev Polynomials

Farinaz Mostajeran, Salah A. Faroughi — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Multilayer perceptron (MLP) networks are predominantly used to develop data-driven constitutive models for granular materials. They offer a compelling alternative to traditional physics-based constitutive models in predicting non-linear responses of these materials, for example, elastoplasticity, under various loading conditions. To attain the necessary accuracy, MLPs often need to be sufficiently deep or wide, owing to the curse of dimensionality inherent in these problems. To overcome this limitation, we present an elastoplasticity informed Chebyshev-based Kolmogorov–Arnold network (EPi-cKAN) in this study. This architecture leverages the benefits of KANs and augmented Chebyshev polynomials, as well as integrates physical principles within both the network structure and the loss function. The primary objective of EPi-cKAN is to provide an accurate and generalizable function approximation for non-linear stress-strain relationships, using fewer parameters compared to standard MLPs. To evaluate the efficiency, accuracy, and generalization capabilities of EPi-cKAN in modeling complex elastoplastic behavior, we initially compare its performance with other cKAN-based models, which include purely data-driven parallel and serial architectures. Furthermore, to differentiate EPi-cKAN's distinct performance, we also compare it against purely data-driven and physics-informed MLP-based methods. Lastly, we test EPi-cKAN's ability to predict blind strain-controlled loading paths that extend beyond the training data distribution to gauge its generalization and predictive capabilities. EPi-cKAN achieves superior accuracy in predicting stress components and generalizes well under blind strain-controlled loading paths. It maintains robustness to noise, achieving only 1.52% error in deviatoric stress predictions with 5% noisy data, outperforming MLP models.

Strain Type‐Curve Analysis During Recovery Using Evolutionary Polynomial Regression for Evaluating Confined Reservoir Properties

Soheil Roudini, Lawrence C. Murdoch, Scott DeWolf — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Pressure changes in reservoirs lead to strain in the overlying confining unit, which can be measured near the ground surface using high-precision strainmeters. We propose a methodology that adapts the classic Agarwal type curves used for analyzing recovery pressure data to interpret strain data. Poroelastic analyses indicate that plotting components of the strain tensor as a function of Agarwal time creates semi-log straight lines. The average horizontal and vertical strains intersect the zero-strain axis at times that are similar to the times determined using a similar analysis of the pressure. The intersection time gives a direct estimate of the hydraulic diffusivity. The relationship between the transformational strain and reservoir permeability, specific storage and porosity-to-fluid compressibility ratio was established using an Evolutionary Polynomial Regression (EPR) model. The model was trained and validated for different scenarios with the outlined reservoir parameters as inputs and simulated transformational strain as outputs. The result is an accurate model with good generalization power that will be used with strain data to estimate the bulk modulus of the solid and fluid and Poisson's ratio by assuming permeability is available from transient pressure well testing or other independent sources. The prediction and measurement uncertainties were also included in the solution process, leading to a distribution of the estimated parameters. The method was validated using (1) datasets from an idealized example created with a poroelastic simulator, and (2) field data measured at the North Avant Field during a recovery test conducted in a 530-m reservoir.

Lattice Discrete Particle Model (LDPM): Comparison of Various Time Integration Solvers and Implementations

Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

This article presents a comparison of various implementations of the Lattice Discrete Particle Model (LDPM) for the numerical simulation of concrete and other heterogeneous quasibrittle materials. The comparison involves the use of transient implicit and explicit solvers and steady-state (static) solvers as well as implementations for central processing unit (CPU) and graphics processing unit (GPU). The various implementations are compared on the basis of a set of benchmarks tests describing behaviors of increasing computational complexity. They include elastic vibrations, confined strain-hardening compressive response, tensile fracture, and unconfined strain-softening compressive response. Metrics of interest extracted from the simulations include macroscopic stress versus strain responses, computational times, number of iterations, and energy balance error. Pairwise comparison of final crack patterns is provided through the correlation coefficient and normalized root mean square error of the crack opening vectors. Moreover, for the most numerically challenging case of unconfined compression with sliding boundary conditions, the stability of the strain-softening response is tested by perturbing the solutions as well as changing the convergence criteria and time step size. Attached to this paper is the complete input data of the benchmark tests; this will allow researchers to run the examples and compare them with their own implementations. In addition, most of the reported implementations are publicly available in open source packages.

Experimental and Numerical Simulation Study on Cross Interface Propagation Behavior and Main Control Mechanism of Tensile Cracks in Bi‐Granite

Xianzhong Li, Bing Liu, Zhenhua Li, Shuai Heng, Xiaodong Zhang, Yinnan Tian — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

This study investigated cross-interface crack propagation mechanisms under tensile loading through integrated laboratory experiments and numerical simulations. Mineral compositions and grain characteristics of bi-material granite (bi-granite) were analyzed using X-ray diffraction (XRD) and polarized light microscopy. Interface parameters were calibrated via Brazilian splitting tests, with a heterogeneous grain-based model (GBM) developed through mineral-boundary-interface hierarchical calibration. Particle Flow Code (PFC) simulations systematically explored interface cementation strength (N = 0.6–2) and inclination angle (θ = 0°–90°) interactions. Results indicate tensile strength follows non-monotonic angular dependence peaking at θ = 30°. Interface-aligned propagation dominates under N ≤ 0.8 or θ ≤ 30°, transitioning to through-interface penetration at N ≥ 1.4 or θ ≥ 60°. Crack evolution demonstrates strength-energy dual control, where inclination angles regulate tensile-shear conversion via stress field restructuring, accompanied by nonlinear critical threshold evolution. Concurrently, increased mica content significantly reduces tensile strength, while the inherent brittleness of quartz and feldspar intensifies stress concentration effects. These mechanistic insights advance the optimization of hydraulic fracturing strategies in deep geothermal reservoirs.

Analytical Prediction of Ground Settlement Induced by Shield Tunneling in Upper‐Soft and Lower‐Hard Inclined Strata

Pengfei Li, Jiannan Xie, Shuang Chen, Fei Jia — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

The stability of shield tunneling through inclined strata composed of a soft upper layer and a hard lower layer represents a critical challenge in current underground engineering practice. This study proposes a theoretical framework for predicting surface settlement induced by shield tunneling under such geological conditions. First, a generalized model for the radial convergence of the surrounding soil is developed, and analytical expressions for the convergence center are derived for eight representative shield tunneling configurations commonly encountered in stratified ground. Next, the applicability of the classical Peck formula is evaluated using one-dimensional linear regression analysis, tailored to the characteristics of upper-soft and lower-hard inclined strata. Based on this analysis, an analytical expression for surface settlement is established to account for the specific mechanical behavior of the composite strata. The proposed methodology is validated through a case study of the second Jiaozhou Bay Subsea Tunnel project in Qingdao, Shandong Province, utilizing both numerical simulations and in-situ monitoring data. Results reveal that the maximum settlement and the offset of the settlement trough play distinct roles in shaping the overall deformation profile, with their relative significance varying across different strata configurations. These findings underscore the importance of considering both parameters in engineering practice. The proposed analytical model provides a reliable and practical tool for surface deformation prediction, offering empirical support for both real-time assessment and preemptive risk management in shield tunneling projects.

Numerical Simulation of Dynamic Mechanical Behavior and Damage Evolution Mechanisms in Granite Following High‐Temperature Water‐Cooling

Jianli Cao, Yongyi Fang, Gang Wang, Bingchen Han, Zirui Xiang, Hangli Gong — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

To investigate the influence mechanism of high-temperature water-cooling on the dynamic mechanical behavior of granite, a combined approach of impact loading experiments and discrete element simulations was employed. The study systematically analyzed the dynamic fracture behavior and thermo-mechanical damage mechanisms of granite after high-temperature water-cooling treatment. The results indicate that heat-treatment temperature and impact velocity exert a synergistic influence on the dynamic response of granite. A critical temperature of approximately 450°C was identified for dynamic peak stress: below this threshold, the stress variation remains moderate, while above it, a sharp decrease occurs. Increasing impact velocity significantly enhances the strain-rate effect; however, this effect is weakened under high-temperature conditions. An inflection point in the proportion of dissipated energy appears near 600°C, and the failure mode transitions from blocky splitting at low temperatures to pulverized fragmentation at high temperatures. A thermo-mechanically coupled grain-based model (GBM) was developed to reproduce the experimental observations, revealing that the rapid increase in transgranular cracks beyond 450°C leads to a sharp reduction in crack initiation stress. By distinguishing the respective contributions of intergranular and transgranular cracking, a thermo-mechanical damage evolution model was established. The analysis shows that intergranular cracks dominate in the low-temperature stage, whereas transgranular cracks become predominant at higher temperatures, resulting in intensified damage. This study provides a theoretical foundation for the safety assessment of deep geothermal energy exploitation.

Phase Field Modeling of Elastoplastic Damage Evolution in Soft‐Hard Interbedded Rock Tunnels Under Hydro‐Mechanical Coupling

Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Soft-hard interbedded rock formations present significant challenges to tunnel stability due to their pronounced lithological heterogeneity and complex coupled hydro-mechanical behaviors. This study develops a coupled hydro-mechanical phase field model to investigate damage evolution and seepage behavior in porous elastoplastic geomaterials. The plastic deformation of the solid skeleton is described using the Drucker–Prager yield criterion, and an improved volumetric-deviatoric strain energy decomposition that accounts for initial geostress is introduced to prevent spurious damage under high compressive stress states. The model is implemented in ABAQUS through user-defined element (UEL) and user-defined material (UMAT) subroutines, utilizing a staggered solution scheme. The proposed framework is validated against analytical solutions and experimental benchmarks. It is subsequently applied to tunnel excavation in soft-hard interbedded formations with varying bedding angles. The results demonstrate that excavation-induced damage localizes preferentially along soft interbeds and is primarily governed by plastic deformation, leading to a permeability enhancement of several orders of magnitude and a strongly coupled evolution of pore pressure. The bedding angle significantly influences the spatial distribution of damage, displacement, and pore pressure, inducing asymmetric mechanical and hydraulic responses that intensify with increasing bedding inclination. Maximum tunnel deformation and lining tensile stress occur at a bedding angle of 45°. Furthermore, the pore water pressure in the tunnel near-field exhibits a two-stage evolution characterized by rapid post-excavation dissipation followed by gradual stabilization, with the direction of dissipation governed by bedding-controlled permeability anisotropy.

Stability Analysis of Longitudinal Inclined Tunnel Faces in Reinforced Soft Soil Strata: A Coupled Theoretical and Numerical Investigation

Qilong Song, Dong Su, Ruixiao Zhang, Yijun Tan, Xiangsheng Chen — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

For inclined tunnels, the longitudinal inclination angle plays a crucial role in influencing the pressure gradient within the chamber, causing substantial pressure fluctuations and thereby elevating the risk of instability during shield tunneling. It is, therefore, necessary to consider the impact of the inclination angle on tunnel face stability. In this study, the FEM was initially adopted to examine the effect of varying inclination angles on the failure process and mechanism in soft soil reinforced by three-shaft stirring piles (TSP). Theoretical models of morphological evolution relative to inclination angle were developed based on the limit equilibrium method (LEM), namely the depression angle reinforcement model (DR model, α < 0), flat angle reinforcement model (FR model, α = 0), and elevation angle reinforcement model (ER model, α > 0). The proposed models were validated by comparing them to relevant theoretical models and field monitoring data. The key findings of this study are as follows: (1) Limit support pressure (LSP) was observed to increase linearly with the inclination angle, indicating that a depression angle (α < 0) is more favorable for maintaining tunnel face stability compared to an elevation angle (α > 0); (2) LSP was found to be inversely proportional to cohesion (c) and the friction angle (φ) while being directly proportional to both the buried depth ratio (C/D) and the normalized additional load (σ_s /γD); and (3) predicted pressure provides a relatively accurate and reasonable warning value for chamber pressure during the construction of the Zhuhai Mangzhou Cross-Sea Tunnel.

A Stabilized and First‐Order Consistent Smoothed Particle Hydrodynamics for Coupled Flow‐Deformation Analysis of Saturated Porous Media

Tiancheng Tong, Xin Gu, Panyong Liu, Xiaozhou Xia, Qing Zhang — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Based on the u−w−p${{\bf u}} - {{\bf w}} - p$ formulation, this paper presents a two-phase smoothed particle hydrodynamics (SPH) framework for modeling the coupled flow-deformation interactions and large deformation behavior in saturated porous media. The pore water pressure is advanced under weak compressibility via the pressure evolution equation, and the seepage velocity obeys Darcy's law as a primary variable, thus facilitating boundary conditions. To enhance accuracy and numerical robustness, the enhanced finite particle method (FPM) discretization and pressure diffusion stabilization are introduced. Then, we test the framework on four standard problems: Terzaghi's 1D consolidation, a 2D strip-loading seepage case, self-weight collapse of a saturated block, and saturated granular-column collapse. These tests check the boundary handling, pressure-field accuracy, and control of spurious oscillations. In all cases, the results agree with the references; the near-boundary solution is better behaved, and pressure oscillations are reduced, especially for low permeability or a large water bulk modulus. Furthermore, the favorable numerical results suggest the potential applicability of the proposed framework to real-world problems, such as landslides and debris flows.

Hydraulic Fracturing Roof Cutting and Pressure Relief for Controlling Mining‐Induced Cross‐Cut Deformation

Wu Xuewu, Zhenqian Ma, Yuankun Zhu, Yunlin Shuai, Yuxiang Bao, Hui Wang — Wed, 13 May 2026 05:17:25 -0700

ABSTRACT

Under complex deep mining conditions, crosscuts adjacent to goafs often face severe surrounding rock stability issues due to the hanging of hard roofs and mining disturbances. Taking the large deformation of the 261 cross-cut at Huoshaopu Coal Mine as an example, hydraulic fracturing for roof cutting and pressure relief was applied for control. Through integrated field observation, theoretical modeling, numerical simulation, and engineering practice, it was found that the depth of roof fractures reached 6.23 m, with an integrity coefficient as low as 0.4–0.5. A cantilever beam model was established and stress formulas were derived, while UDEC simulations verified the effectiveness of hydraulic fracturing in cutting off the roof and redistributing stress. On-site implementation of bolt-grouting reinforcement combined with the “retreat-style single-borehole multi-stage fracturing” technique successfully severed the main roof cantilever, leading to a significant reduction in abutment pressure: coal pillar stress decreased from 39.35 to 32.35 MPa (a reduction of 17.8%), and solid coal side stress decreased from 31.05 to 27.02 MPa (a reduction of 13.0%). Roadway convergence rates were reduced by 28%–38% without any collapse. The study demonstrates that hydraulic fracturing is an effective method for mitigating stress and deformation in crosscuts, providing a critical engineering strategy for controlling thick and hard roof strata.

Issue Information

Wed, 13 May 2026 05:17:25 -0700

International Journal for Numerical and Analytical Methods in Geomechanics, Volume 50, Issue 8, Page 3277-3279, 10 June 2026.

Incorporating Non‐Associated Flow Rule Using Kinematics Based Finite Element Limit Analysis for Plane Strain Problems

Vijaya Sree Korada, Jyant Kumar — Tue, 12 May 2026 04:30:42 -0700

ABSTRACT

It is understood that most soils follow non-associated flow rule, and the true volumetric strain is often considerably lower than that predicted with the application of the associated flow rule. For obtaining the solution for any stability problem with the usage of non-associated flow rule, it is generally recommended to use equivalent values (c∗,ϕ∗${{c}^*},{{\phi }^*}$) of cohesion and internal friction angle for a given dilatancy angle (ψ$\psi $) with the usage of the fictitious associated flow rule. The choice of the flow rule, however, affects the kinematics based finite elements limit analysis (FELA) solution; the solution obtained with the usage of the kinematics conditions becomes the upper bound (UB) solution for an associated flow rule material. In the current article, the usage of the non-associated flow rule has been incorporated while employing the kinematics based FELA. To show the implementation procedure, the bearing capacity of a rough strip footing placed on cohesionless media and subjected to an inclined load has been computed with the usage of the second order cone programming (SOCP) for performing the associated optimization. The computations clearly reveal that the magnitude of the failure load reduces continuously with a decrease in ψ$\psi $ and this computed value of the failure load, especially for small values of ψ$\psi $, remains generally substantially greater than that obtained simply with the usage of c∗${{c}^*}$ and ϕ∗${{\phi }^*}$ and using the fictitious associated flow rule.

Study on Fluid‐Solid Coupling Simulation and Comprehensive Treatment of Coal Gangue Pile Slope Slip Process Induced by Rainfall Infiltration

Ping Liu, Zhenzhi Liu, Jie Liu, Zhenglong Li, Rui Chen — Tue, 12 May 2026 04:27:27 -0700

ABSTRACT

As a loose, engineered deposit with multiple terraces and a wide grain size distribution, coal gangue piles exhibit stability characteristics that differ from those of conventional rock and soil slopes. This study focuses on the gangue pile at the Min'an Coal Mine in Guizhou and employs a CFD-DEM fluid-structure interaction numerical simulation method to investigate the mesoscale mechanical mechanisms underlying rainfall-induced slope slippage and instability. The study reveals that under rainfall infiltration, internal cracks in the slope exhibit a spatial distribution characterized by high density at the toe and low density at the crest. The initiation angles of micro-cracks closely align with the macro-scale slip direction and tend to propagate along existing fracture planes. By the time the simulation reaches Step (50 × 10⁴), the maximum particle displacement reaches 20.16 m, triggering a pull-type failure mode that propagates downward from the crest. Detailed stress analysis indicates that the toe is the most mechanically sensitive region of the stepped slope. Rainfall infiltration causes a sharp decrease in effective interparticle contact force chains in this area, resulting in severe fluctuations in stress for both coarse and fine particles and a sudden increase in shear stress, which ultimately induces skeletal instability. This study conducted comparative simulation verification on a coal gangue mountain that had undergone comprehensive remediation. The results show that the slope maintains long-term stability even under prolonged heavy rainfall. This study provides valuable insights for the management and stability analysis of similar coal gangue pile slopes.

Effects of Variable‐Thickness Marine Sediment Layer on the Seismic Response of the Seabed: An Analytical Solution

Luchun Wang, Zhendong Shan, Zhinan Xie, Yuheng Li, Xubin Zhang — Sun, 10 May 2026 23:24:15 -0700

ABSTRACT

The seismic response of the seabed is the basis of assessments of the safety of marine engineering structures and seismic geological disasters. However, traditional theoretical analyses often overlook the spatial variations in the thickness of sedimentary layers, which are precisely the geological conditions commonly faced by offshore engineering. To fill this research gap, in this paper, a dynamic interaction model including seawater, a variable-thickness sedimentary layer and underlying bedrock for the oblique incidence of P waves and SV waves is established, and the analytical solution of its steady state seismic response is derived. A parameter analysis of the system revealed that the spatial variation in the thickness of the sedimentary layer significantly amplifies the spatial heterogeneity of the seabed response. Even within a small range of inclines, this difference is particularly prominent near the natural frequency of the system. In addition, the influence of the inclination angle at the interface between the sedimentary layers and bedrock on the displacement response presents a complex dual effect; that is, it may play a significant amplifying or suppressing role at different frequencies, incident angles and spatial positions. This study reveals the controlling role of the variable thickness effect on the seismic response of the seabed. The analytical model provided can offer a more precise theoretical basis for the seismic design of offshore engineering projects under complex seabed conditions.

Instability Mechanism of Expansive Soil Slopes Based on the BExM Model: A Study on the Control Effects of Macro and Micro Parameters

Shuai Xu, Hanjing Jiang, Yongfu Xu — Sun, 10 May 2026 21:34:35 -0700

ABSTRACT

The presence of expansive soil interlayers poses a severe threat to the long-term stability of engineered slopes due to their complex hydro-mechanical behavior. To investigate the intrinsic instability mechanism, this study develops a two-dimensional finite element model of a three-layer slope with an expansive soil interlayer. The slope's response under coupled excavation and impoundment is simulated using the Barcelona Expansive Model (BExM), which effectively captures the double-structure characteristics of expansive soils. A systematic sensitivity analysis is conducted to examine the controlling effects of macroscopic strength and microstructural swelling parameters. The results identify the interlayer as the core weak zone governing slope deformation. The numerical simulations reveal a progressive failure mechanism where plastic strain preferentially initiates at the slope toe and propagates deep along the interlayer, forming a continuous shear band. This internal damage evolution manifests macroscopically as a distinct differential deformation pattern characterized by heave at the toe and settlement at the crest. Furthermore, the study reveals a dual-control mechanical mechanism where slope stability is determined by the interplay between the intrinsic macroscopic shear resistance and the internal wetting-induced swelling drive. In terms of practical engineering, these findings imply that traditional strength-based assessments are insufficient. Effective slope design must explicitly quantify microstructural swelling parameters to accurately predict long-term deformation and prevent progressive failure triggered by hydrological changes.

Complex Dynamics of Hydraulic Fracture Network in Ultra‐Deep Fractured Sandstone Reservoirs in Tarim Oilfield, China

Sat, 09 May 2026 05:18:17 -0700

ABSTRACT

The fractured sandstone reservoirs, exemplified by the Kuqa depression, are rare ultra-deep gas reservoirs found worldwide, and constitute the primary natural gas reserves of the Tarim oilfield, China. The target reservoir exhibits low matrix porosity and permeability, but is distinguished by well-developed natural fractures. Hydraulic fracturing is a crucial method for achieving its effective development. Field practices have demonstrated that the properties of natural fracture groups (NFGs) are significant controlling factors influencing gas well production in this region. However, the existing comprehension of how NFG properties influence hydraulic fracturing outcomes remains obscure. Therefore, taking the case of ultra-deep fractured sandstone from Well A located in the Kuqa depression, this paper constructs NFGs and subsequently incorporates it into a three-dimensional fracturing model. Based on this integration, we have developed a comprehensive and fully-coupled hydraulic-mechanical numerical model tailored for simulating network fracturing. The reliability of the simulation results is verified using microseismic monitoring data and on-site injection pressure. Furthermore, the propagation dynamics of hydraulic fracture network in fractured formations composed of single or conjugate orthogonal NFG(s) are analyzed, respectively. The effects of crucial parameters, including natural fracture density, strike, aspect ratio, and injection rate, are explored. The study uncovers that high natural fracture density, low strike, and large injection rate favor the formation of complex hydraulic fracture networks. By selecting formations with large natural fracture strike and suitable aspect ratios as fracturing sweet spots, deep-penetration stimulation is effectively achieved.

Phase‐Field Modeling of Chemically Assisted Crack Propagation

Giancarlo P. Ventura, Ronaldo I. Borja — Sat, 09 May 2026 05:17:42 -0700

ABSTRACT

We employ the phase-field technique to model the time-dependent crack propagation induced by combined mechanical loading and solid dissolution. Chemical dissolution causes the porosity of the solid to increase, thereby degrading its strength, stiffness, and fracture toughness. To accommodate the influence of porosity on the chemomechanical response of the solid, we employ a novel three-field solid displacement-phase-field variable-solid porosity finite element formulation with equal-order interpolation on all three independent variables. The model is validated against test results on a rock sample with a notch subjected to three-point bending, which shows degrading strength and stiffness of the sample with prior CO2${\rm CO}_2$ exposure. The model is also used to investigate the effect of degrading fracture toughness, evaluated from a degrading J$J$ integral, on crack propagation in a rock with a blunted tip. The rate of chemical dissolution is determined from the transition state theory that gives rise to time-dependent processes such as creep and stress relaxation in fractured rocks, in addition to the viscous response inherent in the bulk material.

Numerical Study on the Fully Mechanized Rapid Construction Method for Subsea Tunnel

Jian Ni, Xin Gao, Yuxue Chen, Hongliang Liu, Hui Cai, Wenfeng Tu — Sat, 09 May 2026 02:46:34 -0700

ABSTRACT

This paper presents a case study of a super-long subsea tunnel in Jiaozhou Bay, Qingdao, China. To address key technical challenges in the fully mechanized rapid construction of super-long subsea tunnels, this study systematically investigates the optimization of excavation methods and support installation distance across different rock grades by integrated numerical simulation and field monitoring. A numerical model was developed to analyze deformation response and stability under classes III, IV, and V surrounding rock conditions using both bench method and full-face methods, supplemented by multi-scenario construction step tests. Results indicate that the full-face method is suitable for class III rock without strict support distance requirements, where lining can be applied based on monitoring data and construction plans; For class IV rock, the full-face method is recommended in stable sections, while the bench method should be used in fractured zones, with initial support closure limited to ≤70 m and secondary lining to ≤250 m from the excavation face; For class V rock, the bench method is advised, with initial support closure within ≤60 m and secondary lining within ≤240 m from the excavation face. Field monitoring confirmed that surrounding rock deformation remained within design limits, and initial support performed effectively, validating the proposed methods and distance criteria. This study provides theoretical and practical guidance for fully mechanized construction in similar subsea tunnel projects.

Reply to Discussion on “Seismic Bearing Capacity of Strip Footing on Excavations Considering Soil Strength Anisotropy Using Modified Pseudo‐Dynamic and Pseudo‐Static Approaches”

Thu, 07 May 2026 05:53:42 -0700

International Journal for Numerical and Analytical Methods in Geomechanics, EarlyView.

An Efficient Strength Criterion Based Constitutive Model for Geomaterials: Development and Application

Wanqing Shen — Wed, 06 May 2026 08:50:16 -0700

ABSTRACT

Porosity is a fundamental property of geomaterials and significantly influences their overall mechanical behavior, including yield strength and volumetric deformation. In this study, a general elliptic macroscopic yield criterion with an explicit and simple form is proposed for geomaterials, based on their yield behavior under tensile and compressive hydrostatic loadings. This criterion is then applied to a porous material whose matrix follows the Drucker–Prager model, characterized by tension-compression asymmetry. It explicitly incorporates both porosity and matrix properties. Despite its simplicity, the proposed criterion demonstrates strong robustness and high accuracy, as validated by finite element simulations over a wide range of frictional parameters and porosity values. Building on these promising results, a complete elastoplastic constitutive model is developed, incorporating appropriate plastic hardening and flow rules. The model is applied to characterize the mechanical behavior of porous sandstone and is validated through comparisons with experimental data under various confining pressures. Furthermore, it successfully captures the evolution of microstructure throughout the loading process.

Discussion on “Seismic Bearing Capacity of Strip Footing on Excavations Considering Soil Strength Anisotropy Using Modified Pseudo‐Dynamic and Pseudo‐Static Approaches” by Shabnam Shirazizadeh, Amin Keshavarz, Majid Beygi, Mohammad Saberian, Jie Li, and Ramin Vali, International Journal of Numerical and Analytical Methods in Geomechanics 2024, 0:1–15

G. Gowtham, Jagdish Prasad Sahoo — Wed, 06 May 2026 08:20:34 -0700

International Journal for Numerical and Analytical Methods in Geomechanics, EarlyView.

Numerical Modeling of Geological Fault Reactivation Using Sequential Coupling Strategies

Julio Rueda, Cristian Mejia, Roberto Quevedo, Deane Roehl — Wed, 06 May 2026 05:41:09 -0700

ABSTRACT

The interaction between fluid flow and mechanical deformation in fault zones can lead to processes of fault reactivation, triggering potential geomechanical problems such as seismicity, well collapse, fluid migration to shallower layers, and aggravated surface subsidence. During the production phase, fluid injection/production alters the stress state near a geological fault, which may compromise the integrity of initially sealed faults. Some approaches based on either one-way or fully implicit analyses have been used to predict the reactivation of geological faults. Fully-implicit approaches are, in theory, the most accurate because the governing equations are solved conservatively in a single system. However, their application is restricted owing to several issues, such as convergence and computational effort. On the other hand, one-way analyses are easy to implement and provide solutions at lower computational costs. Unfortunately, they trigger inaccurate results depending on the coupling level between fluid flow and geomechanics. This work proposes two-way sequential coupling strategies based on fixed stress rates for forecasting fault reactivation and leakage. Such strategies are implemented through explicit and iterative techniques between fluid flow and geomechanics. The implemented coupling strategies are verified against relevant numerical solutions by simulating a reservoir production problem and the fault reactivation analyses. Then, all strategies are compared in terms of accuracy, stability, and computational time. The results show that the proposed two-way sequential strategies overcome the drawbacks of the one-way and the fully implicit approaches and can be used for practical engineering applications.

Loess–Fiber Interfaces in Direct Shear: An Energy‐Consistent Traction–Separation Framework for Parameter Identification

Yuxin Zhao, Wanli Xie, Kangze Yuan, Hui Yang, Qiqi Liu, Xinyu Li — Wed, 06 May 2026 03:43:00 -0700

ABSTRACT

Accurate assessment of deformation in fiber-reinforced loess requires a reliable contact-scale traction–separation law. Predictive accuracy hinges on interfacial parameters, yet estimates derived from single-fiber pull-out tests are not representative of the in-situ Loess–fiber interaction. This study formulates a three-dimensional finite-element micromechanical representative element with a single fiber embedded in loess, where the Loess–fiber interface obeys a traction–separation law combining cohesive bonding and frictional sliding, reproducing the interface's shear-stress-displacement response and cumulative frictional dissipation. Within an energy-dissipation framework, cohesive parameters were obtained from test-derived Mode II work. Under the Hill-Mandel condition, directional orientation averaging was used to map the representative-element response to the specimen scale, recovering the macroscopic fiber-contributed shear stress. A parametric suite of three-dimensional finite-element analyses was conducted to obtain the interfacial friction coefficient (μ) and the elastic-slip threshold (ES) in the contact law. Parametric analyses of Loess–fiber interface shear across different normal stress levels demonstrate a transition from bond-controlled resistance to friction-controlled sliding. Higher normal stress delays the onset of friction-controlled sliding. The resulting two-parameter map reveals that μ and ES jointly govern the strength and slip of the interface. Within the tested normal stress range, it delineates a high-strength plateau for μ of at least 0.40, an effective ES range of 0.0035–0.0045, and an optimal contact-scale slip range of 0.3–0.6 mm. The study presents an energy-consistent micro-to-macro traction–separation framework for identifying and validating Loess–fiber interface parameters, supporting design quality control and deformation control in reinforced loess.

Seismic Stability Analysis of Embankment Supported by Geosynthetic‐Encased Stone Column Composite Foundations

Xiaocong Cai, Ling Zhang, Zijian Yang — Tue, 05 May 2026 00:36:32 -0700

ABSTRACT

Geosynthetic-encased stone columns (GESCs) can effectively improve the performance of the foundation in seismic zones to enhance the safety and stability of superstructures. This study establishes a comprehensive probabilistic framework to quantify the seismic instability probability (PI) of embankments supported by GESC composite foundations. The parameterized seismic stability functions are derived from the logistic regression and seismic stability model. Key parameters include column diameter (D_c ), tensile strength (T), area replacement ratio (m), strength parameters of column (φ _c and c _c), surrounding soil (φ _s and c _s), and embankment (φ _em and c _em), and slope ratio (H_em/L_slope ). Results indicate that the reinforcement effect of geosynthetic reflects on increasing cohesion related to D_c and T. Reduced column diameters (e.g., decreasing D _c by 0.504 m) combined with high-strength geosynthetic (e.g., increasing T by 33.73 kN/m) optimize seismic resilience for a 0.1 rise in k _h. m reduces PI with a regression coefficient of −39.303, making it 18.9 times more influential on system performance than embankment geometry. Enhancing c _em improves stability 5.2 times more effectively per unit change than optimizing φ _em. Embankment performance governs system behavior compared to the strength parameters of the surrounding soil and column under low-m conditions (e.g., ≤ 5%).

A Coupled Chemohydraulic Model of a Hydration Experiment

Emmanuel Detournay, Vaughan Voller — Thu, 30 Apr 2026 06:28:03 -0700

ABSTRACT

This article presents a model for the hydration of periclase into brucite during water infiltration into a dry, pure periclase core. The hydration process proceeds in two stages. In Phase I, an infiltration front advances through the core while simultaneously triggering the hydration reaction. Phase II begins once the front reaches the downstream end of the core and continues until hydration is complete. Asymptotic analysis shows that, at early times, the infiltration front advances proportionally to the square root of time. This behavior breaks down at intermediate times. At sufficiently large times, however, and provided that the Damköhler number—defined as the ratio of hydraulic to reaction timescales—is large and the infiltration front has not yet traversed the core, the front again exhibits a square-root-of-time scaling. In this late-stage Phase I regime, the hydration reaction becomes increasingly localized in a narrowing zone immediately behind the advancing infiltration front, accompanied by a sharpening gradient in the degree of reaction. A numerical solution of the governing equations confirms and quantifies the asymptotic predictions. The numerical method combines a finite difference scheme with a weak formulation of the balance condition at the moving front. Because the extent of reaction serves as a proxy for the eigenstrain associated with the volumetric expansion of the hydrated mineral, and because gradients in eigenstrain at the hydration/infiltration front control the magnitude of induced tensile stresses, the model provides a key theoretical framework for interpreting experimental observations that core damage intensifies with increasing Damköhler number.

State‐Equivalent Compaction of Dam Rockfill: Experimental Method, Constitutive Formulation and Numerical Case Study

Mon, 27 Apr 2026 02:07:09 -0700

ABSTRACT

This study demonstrates that the pressuremeter modulus can serve as a practical state descriptor for rockfill and can be used directly in constitutive analysis. Large-scale pressuremeter model tests on two gradations established a clear, monotonic relation between pressuremeter modulus and dry density. Using this relation, densities corresponding to target moduli of 75 and 90 MPa were selected for drained triaxial tests. The results reveal an equal-modulus equivalence for the two scaled gradations tested: once specimens are compacted to the dry densities corresponding to the same pressuremeter modulus, their stress–strain and volumetric responses become practically indistinguishable across these gradations. These conclusions are drawn from tests on only two scaled materials derived from the same prototype rockfill, so the observed equivalence should not yet be regarded as universal. Building on this finding, we integrate the pressuremeter modulus into a standard hypoplastic formulation through a minimal two-part enhancement: a state normalisation of the density measure and a stiffness-scale alignment, achieved by scaling the granular hardness parameter in proportion to the measured modulus. The tensorial structure and calibrated constants of the reference model remain unchanged; only zone-wise state inputs derived from field or laboratory modulus are required. With one parameter set calibrated at 75 MPa, the framework reproduces element tests at both target moduli and is implemented in a three-dimensional embankment model of the 298 m Lianghekou rockfill dam. Predicted settlement profiles during staged construction closely match monitoring, capturing both the magnitude and the curvature of the settlement troughs and the observed flattening in zones that achieved higher modulus. A baseline analysis without modulus-based normalisation shows systematic bias, underscoring the value of the proposed integration.

Simplified Simulation Method and Practical Prediction Tool for Mechanized Tunnelling Induced Settlements Based on Hybrid Volume Loss‐Grouting Pressure Method

Chengwen Wang, Xiaoli Liu, Nan Hu, Wenli Yao, Enzhi Wang, Guohui Yan — Sat, 25 Apr 2026 04:31:57 -0700

ABSTRACT

Settlement prediction is crucial in the design and construction of mechanized tunnels, with numerical simulation serving as an effective tool for estimating settlement trough. This study proposes a simplified two-dimensional simulation method as an alternative to complex and time-consuming three-dimensional simulations for predicting settlement trough. By integrating the volume loss method and grouting pressure method, this study introduces a hybrid volume loss-grouting pressure (VL-GP) method, a two-dimensional simplified simulation approach for estimating settlement in single and twin mechanized tunnels. The proposed method was validated using six historical cases, demonstrating its advantages over other simplified simulation methods in accurately reflecting the construction process and improving prediction accuracy. A parameter study on the hybrid VL-GP method examined the influence of soil properties, tunnel geometry, and construction parameters on settlement troughs in mechanized tunnels. Results indicate that clay exhibits greater sensitivity than sand, emphasizing the need to consider multiple factors when using settlement control as a design and construction criterion. To facilitate the application of the hybrid VL-GP method, a graphical user interface (GUI) was developed using FLAC3D and Gmsh, integrating Python and Fish programming to provide a user-friendly tool for predicting and evaluating induced settlement in mechanized tunnels.

Thermo‐Hydrodynamic Processes of Microparticles in Fractures: A CFD–DEM Approach

Hoai Thanh Nguyen, Pania Newell — Thu, 23 Apr 2026 09:00:44 -0700

ABSTRACT

Controlling fracture permeability plays a critical role in subsurface energy applications, particularly in geothermal energy production and enhanced carbon sequestration, where regulating fluid flow is essential. The use of microcapsules has become a promising solution to enhance fracture permeability by providing a controlled sealing mechanism. This study employs a coupled Computational Fluid Dynamics Discrete Element Method (CFD-DEM) approach to investigate the thermo-hydro transport behavior of microcapsules in fractured environments, focusing on the influence of temperature, particle size, and concentration. The results show that temperature significantly affects microcapsules transport dynamics, with low temperatures promoting clustering due to increasing fluid viscosity, while high temperatures lead to excessive dispersion and reduce sealing. The medium temperature conditions create a balance between mobility and clustering, which controls the sealing behavior to suit the desired goal. Additionally, large microcapsules exhibit stronger sealing characteristics, whereas small ones maintain high mobility but are less effective for sealing. An interesting stagnation effect is also observed for medium size microcapsules, where the interaction of drag, inertia, and gravity can contribute to the control of the sealing behavior of the particles. Furthermore, high microcapsule concentrations can enhance aggregation at low temperatures, but may cause over-dispersion at high temperatures, due to the collisional forces between the particles. These findings are extremely valuable for devising conditions for particles suitable for different purposes in controlling the transport and sealing behavior of particles in fractures in geothermal environments.

Consolidation of the Saturated Composite Foundation With Periodic Reinforcing Piles by the FHFE Method

Jian‐Fei Lu, Yang Liu — Mon, 20 Apr 2026 06:42:05 -0700

ABSTRACT

The consolidation of the saturated composite foundation with periodic reinforcing piles (CFPP) under external loads is fundamental for the design of the composite foundation. To investigate the consolidation of the CFPP subjected to an arbitrary load accurately, the pseudo-periodic property for the CFPP under a spatially harmonic load is introduced and proved in this study. Based on the pseudo-periodic property of the CFPP, the Fourier harmonic finite element (FHFE) method for the CFPP is developed. To develop the method, the response of the CFPP to a spatially harmonic load is decomposed into a series of Fourier harmonics first. Then, by using the Biot's theory and virtual work principle, the FEM equations for each Fourier harmonic of the CFPP are established. By introducing the impendence matrix for the underlying half-space bedrock, the coupled FEM equations for the Fourier harmonic of the CFPP and bedrock in the Laplace domain are developed. Solution of the coupled FEM equations for the Fourier harmonics in the Laplace domain and inversion of the Laplace transform yield the time-spatial domain response of the CFPP to a spatially harmonic load. The total response of the CFPP to an arbitrary load can then be determined by synthesizing all the responses of the CFPP to the corresponding spatially harmonic components of the arbitrary load. With the proposed FHFE method for the CFPP, the influences of the permeability and shear modulus of the piles, spacing between the piles as well as load types are investigated.

An Analytical Approach for Predicting Vapor Migration Induced by Pot Cover Effect With Field Test Validation

Xiao Qu, Yanfei Zhang, Ke Shi, Daniel Dias — Mon, 20 Apr 2026 06:25:00 -0700

ABSTRACT

Pot Cover effect describes a process in which vapor migrates upward along a temperature gradient, condenses and accumulates as liquid water or ice at the base of a covering impermeable layer, ultimately resulting in pavement damage. Although numerical simulation, analytical calculation and empirical models are widely used to calculate vapor migration caused by Pot Cover effect, there are limitations in their computational efficiency under specific conditions. To overcome this limitation, an analytical approach based on Fick's law and fundamental physical assumptions is developed to quantitatively describe vapor migration. Validation using field test data from Beijing Daxing International Airport confirms the accuracy of this approach in capturing vapor migration in freezing unsaturated soils. Furthermore, the analytical approach is applied to investigate the influence of the separation layer's depth and gas permeability on vapor migration. The optimal configuration is identified as a layer positioned at the maximum freezing depth (40 cm in this study) with nearly 0% gas permeability, which most effectively inhibits vapor migration induced by Pot Cover effect. Finally, by integrating analytical and experimental results, the influence of soil gas permeability, initial water content, and dry density on vapor migration is investigated. The analysis indicates that higher initial water content and dry density diminish soil gas permeability, thereby restraining vapor migration and alleviating the water accumulation characteristic of Pot Cover effect. The derived analytical framework provides a practical and efficient tool for designing mitigation strategies against Pot Cover effect in cold-region engineering.

Numerical Identification of the Critical Particle Size for Skeletal Fractions in Fractal‐Graded Soils

Pingfan Wang, Jinfeng Bi, Xianqi Luo, Yunwei Shi, Zhuomin Li — Mon, 20 Apr 2026 05:10:13 -0700

ABSTRACT

Internal stability is an important attribute for granular soils in assessing the sensitivity to suffusion. The particle composition of soil matrix can be used to establish the internal stability criterion. Overviews of current researches on the soil skeleton, the critical particle size for the skeletal fraction is unclear and inadequate, especially for soil matrix with significant fine contents. The content of erodible particles cannot be accurately determined to assert the internal unstable. In this article, a new formula for identifying the critical particle size of soil matrix with a particular particle size distribution is derived analytically. The soil particles are separated into filling and skeletal fractions based on their influence on the matrix volume. A modified experimental method is designed to investigate the separation point of particle fractions using the discrete element numerical simulation. The results indicate that the critical particle size of fractal-graded soil can be expressed as a function concerning particle size ratio and fractal dimension. Particles larger than the critical particle size belong to the skeletal fractions, the remaining particles are the filling fractions that implicate the potential erodible particles in suffusion. A new geometrical criterion is proposed to evaluate whether soil matrix is overfilled by filling fractions based on the critical mass ratio rather than conventional fine content thresholds, which demonstrates broader applicability across widely graded soils. This study will facilitate further research on the internal stability of graded soils, the design of filter layers, and establishing a unified criterion for assessing the sensitivity to suffusion.

A Surrogate Model for Stability Assessment of Two‐Layered Cohesive Slopes

Naloan Coutinho Sampa, Humberto C. F. S. S. S. Volpato — Thu, 16 Apr 2026 23:41:53 -0700

ABSTRACT

This paper introduces a novel surrogate model for rapid stability evaluation of two-layered cohesive slopes under undrained conditions. The model eliminates the need for iterative calculations and slip surface searches, allowing for fast and accurate stability assessments without reliance on advanced numerical tools. The formulation is derived from an extensive parametric study using the Morgenstern–Price limit equilibrium method and is expressed through two physically meaningful dimensionless parameters: a stability number Ns,1${{N}_{{\mathrm{s}},1}}$ and a strength-contrast ratio Rcu${{R}_{{\mathrm{cu}}}}$. These parameters directly govern the factor of safety, while a critical strength ratio Rcu,t${{R}_{{\mathrm{cu}},{\mathrm{t}}}}$ delineates the transition between shallow (upper-layer) and deep (two-layer) failure mechanisms. The model is validated against SLOPE/W benchmarks and independently corroborated using Slide2 (multiple LEM variants) and PLAXIS 2D (FEM), showing high accuracy (R ² ≈ 0.999) and low error (92% of predictions within ±5%) across 384 slope configurations. Two- and three-dimensional stability charts are provided for immediate visualization and practical use. As a dimensionless, non-iterative surrogate, the model offers high computational efficiency and mechanistic insight, effectively bridging classical stability charts and advanced numerical methods for preliminary design, parametric exploration, and large-scale slope screening.

Numerical Investigation of the Contribution of Different‐Scale Rock Joint Roughness to Shear Strength

Tue, 14 Apr 2026 04:40:59 -0700

ABSTRACT

The shear resistance of rock joints is significantly influenced by the different-scale surface roughness. In this paper, the revised Grasselli's morphological parameters, θG${{\theta }_{\mathrm{G}}}$ and θH${{\theta }_{\mathrm{H}}}$, are demonstrated to describe small-scale unevenness (second-order roughness) and large-scale waviness (first-order roughness), respectively. This provides a more straightforward approach for roughness decomposition of rock joints. Furthermore, the numerical shear tests are conducted using the Particle Flow Code (PFC) to reproduce the shear behavior of rock joints with progressive degradation of two-order roughness. The results indicate that the failure of waviness is governed by the tensile strength of the joint walls, whereas the failure of unevenness is controlled by compressive strength. Based on these findings, a modified shear strength model is developed by extending the joint roughness coefficient-joint compressive strength (JRC-JCS) model. The proposed model is validated through numerical simulations, laboratory direct shear tests, and published data on rock joints with both standard profiles and natural surfaces. Compared with the JRC-JCS model, the proposed model provides a more refined description of joint surface roughness by explicitly distinguishing the contributions of waviness and unevenness. It could predict the peak shear strength more accurately and offers better support for the stability assessment of jointed rock masses.

Study on the Effects of Empty Hole Spacing on Fracture Propagation and Damage Evolution Mechanisms in Multi‐Hole Blasting

Yunjuan Chen, Xiaoyang Liu, Jiarui Su, Jun Wang, Dapeng Qiu, Gaohan Jin — Tue, 14 Apr 2026 04:20:35 -0700

ABSTRACT

The smooth blasting of hard granite tunnel will have problems such as poor fragmentation of the tunnel face. To address these issues, this study investigates the mechanism of empty hole blasting. According to the blasting theory, by deducing the formula of the equivalent damage zone radius of the group hole, and a criterion for defining the blasting effect is proposed. The rationality is verified by numerical simulation and field test. The results show that the empty hole can change the stress distribution of the group hole blasting, and has the effect of directional to crack. With the increase of empty hole-group hole spacing, the peak stress decreases gradually. Aiming at the damage change, the damage feature transformation coefficient m is proposed to define the blasting effect and m = 0.6 is determined as the damage feature transformation threshold. With the increase of distance, the propagation speed and length of rock cracks gradually weaken, and the regional penetration effect gradually deteriorates. The relationship between damage threshold and vibration velocity is constructed. It is concluded that when the space is greater than the damage threshold, the maximum vibration velocity fluctuation interval gradually increases, and the stress wave propagation velocity gradually weakens. The Sadovsky formula of spacing and vibration velocity peak is constructed to characterize the change law. It provides a reference for the optimization of smooth blasting parameters in hard granite tunnels.

Semi‐Analytical Solution for a Lined Non‐Circular Tunnel in Viscoelastic Rock

Hongliang Liu, Xin Gao, Hui Cai, Yuxue Chen, Hongyun Fan — Mon, 13 Apr 2026 06:23:42 -0700

ABSTRACT

Based on the complex variable method and the corresponding principle of viscoelasticity, viscoelastic solutions for the stress and displacement of a lined non-circular tunnel subjected to in-situ stresses and internal water pressure is derived. The basic equations for solving the analytic functions are established according to the stress boundary condition along the inner boundary of the lining and the stress and displacement continuity conditions along the rock-lining interface. The analytic functions are expressed as Laurent series and the Laplace transformation is performed on the basic equation. Herein, the power series method is applied to obtain the linear equations which are expressed by the analytic function coefficients in the Laplace domain. The stress and displacement solutions of tunnel in Laplace domain can be addressed by solving the equations, and then the viscoelastic solutions are obtained through Laplace Inverse transformation. Subsequently, an example for the horseshoe-shaped tunnel is performed. The example used the generalized Kelvin model to simulate the rheological properties of surrounding rock mass. The obtained solution is compared with the numerical solution. The influences of the lateral pressure coefficient and the internal water pressure on the stresses and displacements of lining are analyzed.

A Coupled u–pw SPH Formulation for Hydromechanical Modeling of Retrogressive Landslides and Comparison With a Penalty‐Based Approach

Enrique M. del Castillo, Ronaldo I. Borja, Alomir H. Fávero Neto — Mon, 13 Apr 2026 00:00:00 -0700

ABSTRACT

We present a strongly coupled displacement (u$\bm{u}$) and pore water pressure (pw$p^w$) version of the Biot–Zienkiewicz (u$\bm{u}$–pw$p^w$) equations in saturated porous media for the meshfree Lagrangian smoothed particle hydrodynamics (SPH) method. We propose two distinct formulations using a single particle layer, two-phase framework, one based on a one-step solution of a pressure Poisson equation (PPE formulation) and another allowing compressibility of the fluid resulting in an explicit rate equation for the pore pressure (PR formulation). We discuss both formulations from a numerical perspective and verify them using benchmark problems from poroelasticity, including Cryer's problem, as well as using undrained triaxial tests, where we additionally compare the results against a weakly coupled penalty-based undrained framework for SPH. Beyond the formulations, the focus of this work is on modeling retrogressive landslides in saturated sensitive clays, which are particularly destructive due to their extended runout and fast movement. Our simulations emphasize performing strongly coupled hydromechanical modeling even for quasi-undrained conditions, contrary to the predominant practices in the literature, as the structural features of the landslides change significantly when pore pressure dissipation and coupled effects are included. Additionally, spreads develop under a greater variety of slope conditions as opposed to the more fluidized flowslide type of retrogressive landslides captured when solely considering undrained behavior. Lastly, we apply the PR formulation to explore how slope steepness and height influence deformation modes and apply the framework to simulate the 1994 Sainte-Monique landslide, recreating the topographic profile, runout, and deformation features post-failure.

Microscopic Particle Interaction Mechanisms in Fluidized Soil Inrush Revealed by DEM‐CFD

Xiangdong Meng, Wanghua Sui, Chang Zhou, Binglun Gao — Fri, 10 Apr 2026 04:25:39 -0700

ABSTRACT

Soil inrush is a typical silo-type geohazard. To investigate particle behavior during this process, DEM-CFD numerical simulation was conducted to comprehensively analyze the evolution of velocity fields, stress fields, force chains, and coordination numbers. The results indicate that the arching force chains near the inrush point continuously break and re-form at higher locations as the inrush progresses. The interior of the arch, characterized by rapid particle transport, a sharp stress decrease, and a low coordination number, indicates that the soil mass is highly loosened and experiences continuous particle loss. This loosened instability zone progressively develops upward. Once the instability zone reaches the ground surface, it rapidly expands across the surface, causing surrounding particles to converge toward the center. Based on the evolution of microscopic contact behavior and macroscopic flow characteristics, this study reveals the dynamic transition mechanism of the soil mass. Specifically, five zones with distinct particle-behavior characteristics are identified during the early stage of soil inrush, and a sixth zone subsequently emerges near the ground surface as surface collapse develops. Finally, a soil state model based on the ellipsoid of motion was established and used to delineate the influence range of a documented inrush accident. This study systematically investigates particle behavior during soil inrush and provides guidance for inrush prevention and mitigation in concealed engineering projects.

Simplified Prediction Method for Ground Surface Displacement Caused by Full‐Process Excavation of Quasi‐Rectangular Shield Tunnels

Yongjie Qi, Gang Wei, Haibo Jiang, Jian Zhou, Zhiguo Zhang — Wed, 08 Apr 2026 07:45:41 -0700

ABSTRACT

In order to explore the surface displacement law caused by the entire process of rectangular shield tunneling, the effects of the additional cutterhead thrust (p ₁) of the cutterhead, the shield shell friction (p ₂), the additional grouting pressure (p ₃) at the tail of the shield, and ground loss caused by the quasi-rectangular shield tunneling were considered. The traditional integration method for the above four factors was simplified, and a simplified calculation method for surface displacement values was proposed. Based on the Zhengzhou Metro Line 8 project, the surface displacement values caused by each factor were calculated. The simplified method calculation values were compared and verified with the integration method calculation values and measured data. The influence of parameter changes on the accuracy of displacement calculation values and simplified methods was further analyzed. The results show that the surface displacement values calculated by the simplified method are in good agreement with the values calculated by the integral method and the measured data. The Poisson's ratio of soil (μ), the internal friction angle (φ), and the depth-to-diameter ratio (H _d) are the main parameters that affect the accuracy of the simplified method. The conditions that need to be met to control the calculation error of surface displacement within 5%, 10%, and 20% are given, and the applicable working conditions of the simplified method are summarized.

A Comprehensive Investigation of Particle Gradation Effects on Limiting Void Ratios and Pore Structures of Granular Soils

Wed, 08 Apr 2026 03:47:31 -0700

ABSTRACT

The limiting void ratios (i.e., maximum and minimum void ratios, e _max and e _min) and pore structures of granular soils critically influence their compactness, permeability, and deformation behavior. However, the effects of particle gradation on both macroscopic limiting void ratios and microscopic pore structures remain inadequately quantified. In this study, DEM simulations of the loosest and densest packings of ideal spheres are conducted to isolate gradation effects from particle shape. The combined influences of the coefficient of uniformity (C_u ) and coefficient of curvature (C_c ) on limiting void ratios are systematically investigated, and predictive models are developed to accurately capture these effects, with both interpolation accuracy and extrapolation capability validated. Additionally, particle gradation effects on three-dimensional pore structures are analyzed, revealing that pore size distributions are well described by the Weibull distribution. Predictive models linking Weibull parameters to gradation parameters are also proposed, demonstrating high accuracy across a wide range of gradations. These findings provide quantitative tools for predicting both macroscopic limiting void ratios and pore-scale properties from particle gradation, offering valuable insights for geotechnical design and optimization.

Numerical Investigation of the Influence of Interparticle Cohesion During the Shear Behavior of Granular Soil

Thao Doan, Buddhima Indraratna, Thanh T. Nguyen, Cholachat Rujikiatkamjorn — Wed, 08 Apr 2026 03:14:04 -0700

ABSTRACT

Interparticle cohesive forces play a crucial role in governing the shear behavior of many soils; however, quantifying this effect remains challenging due to limited microscopic insights available from laboratory experiments. In this context, the current study aims to investigate the influence of microscale cohesion on the shear response using the discrete element method (DEM), where the relevant stress, strain, and dilation characteristics are compared with experimental data before conducting a detailed micromechanical analysis. The results successfully replicate important features of a moderately compacted soil under shearing such as strain softening and contraction-dilation responses. Interestingly, cohesion-induced samples exhibit a sustained increase in shear stress even at high shear strain levels; for instance, the residual shear stress in the highly cohesive sample increased by approximately 40% compared to the non-cohesive sample. This occurs because particle-scale cohesion enhances interparticle bonding, leading to higher average contact numbers (coordination number CN) and increased skeletal forces. A key novelty of this study lies in establishing a quantitative correlation between conventional macroscale shear parameters and microscale CN under varying loading and cohesion conditions. This proves that the more cohesive the particles, the stronger the bonding effect with higher CN, consequently resulting in higher shear resistance. Moreover, this trend is exacerbated when the rolling friction of particles is introduced as the coupled effect of microscale cohesion and rolling friction strengthens the soil's resistance to shear deformation.

Development of Safe Cut‐Out Distance Framework for Continuous Miner Operations in Indian Underground Coal Mines: A Numerical Simulation and Field Studies

Tamilprasanth M, Sahendra Ram — Wed, 08 Apr 2026 03:11:55 -0700

ABSTRACT

The continuous miner (CM)-based coal extraction was introduced two decades ago in Indian coalfields. Safe cut-out distance (COD), represents the maximum safe and stable span of a fixed-width gallery excavated in a single pass using CM. The amount of coal that can be cut at once without support defines the successful implementation of CM. The existing guidelines exhibit considerable variation under similar conditions, making it challenging to determine a safe COD. In this research, a simulation study is carried out for 20 selected panels of different coalfields in India, considering strain-softening material properties for the immediate roof to accurately capture the geo-mechanical response. The simulation study found that Rock Mass Rating (RMR), Young's modulus, gallery width, and depth of cover are the most influential parameters in determining safe COD. Safe COD is defined considering a maximum displacement of 5 mm before the installation of roof bolts in the numerical modelling. Multivariate regression analysis is carried out on the basis of the measured safe COD in the models under different conditions, and a formulation is developed with an R ² value of 0.86. The developed formulation is validated in the field through strata monitoring observation and found to predict the safe COD consistently compared to the other available design guidelines. However, this formulation applies only in the absence of weak geological disturbances and is unsuitable for areas affected by such conditions. This newly developed design guideline increase productivity and reduce the cost and time involved in designing the COD in the field.

Stabilized Semi‐Implicit Material Point Method for Hydro‐Mechanical Coupled Large Deformation Soil‐Structure Interaction Analyses

Mon, 06 Apr 2026 07:50:50 -0700

ABSTRACT

Hydro-mechanical coupled analysis of geotechnical problems generally poses stability challenges, particularly for soil-structure interaction problems involving large deformations. This study presents a stabilized semi-implicit MPM (Material Point Method) treatment based on the incremental fractional step approach to suppress the arbitrary and unphysical pressure oscillations commonly encountered in explicit MPM formulations. The proposed treatment alleviates the restrictive constraints on time increment durations imposed by geomaterial permeability. A frictional contact algorithm incorporating a penalty function is also shown to effectively reduce the formation of spurious gaps and numerical fluctuations over soil-structure contact areas. The stability of the semi-implicit MPM treatment is enhanced by introducing artificial compressibility into the pressure Poisson equation, integrating the APIC (Affine Particle-in-Cell) scheme for particle-grid information transfer, as well as adopting the B-bar approach to mitigate volumetric locking. Additionally, an axisymmetric formulation is developed to enable more efficient modeling of selected classical geotechnical problems. The effectiveness and robustness of the proposed framework are demonstrated against a series of benchmark test cases, including coupled, axisymmetric, dynamic, large deformation and soil-structure interaction simulations, considering the Modified Cam-clay constitutive model.

Nonlinear Subgrade Modulus for Longitudinal Deformation of Tunnel Considering Mobilized Strength of Undrained Clay

Hao Bai, Dong‐Ming Zhang, Zhen‐Wei Ye, Hong‐Wei Huang — Mon, 06 Apr 2026 07:44:33 -0700

ABSTRACT

In view of the limitation that the linear subgrade reaction in the current beam-spring model is inadequate for scenarios of tunnel embedded in the soft ground condition with large deformation, this paper proposes a novel model to evaluate the nonlinear subgrade reaction. The model incorporated the nonlinear characteristics of the longitudinal subgrade reaction for tunnel lining in undrained clay by considering the mobilized strength design (MSD). Firstly, the energy equilibrium equation correlating the subgrade reaction with the tunnel displacement is established considering the soil displacement field. By solving the energy conservation equation, the nonlinear behavior of the subgrade reaction is obtained and verified against numerical models, confirming its rationality. Finally, the proposed model is applied into a real case for the analysis of tunnel longitudinal deformation under the effect of nearby deep excavation. Compared with traditional linear subgrade reaction, the nonlinear subgrade reaction proposed in this study achieves a mean absolute error of 1.22 mm between the calculated tunnel deformation curve and field observations, with an accuracy improvement exceeding 47.4%. By explicitly incorporating the progressive mobilization of shear strength with displacement into subgrade reaction calculations, this method demonstrates superior performance in predicting large deformations of tunnels in undrained clay.

Probabilistic Dynamic Analysis of Circular Foundation Embedded in Loose Sand Under Vertical Machine Vibration Considering Soil Spatial Variability

Kouseya Choudhuri, Debarghya Chakraborty — Mon, 06 Apr 2026 07:40:34 -0700

ABSTRACT

The present study investigates the impact of soil spatial variability on the dynamic settling of an embedded circular foundation in loose sand at its resonance frequency under variable-amplitude vertical harmonic machine vibration, utilizing the random finite difference method (RFDM). The resonant frequency was chosen to study the foundation at its worst within the soil spatial variability framework. Both deterministic and probabilistic analyses are executed using FLAC^3D software. The probabilistic analysis assumes a lognormally distributed random field for the elastic modulus (E) of loose sand. The mean dynamic settlement (µ_δ ) and exceedance probability (p_e ) of allowable settlement at different depths of the soil model are evaluated considering different spatially variable parameters (e.g., horizontal scale of fluctuation, L_x = L_y ; vertical scale of fluctuation, L_z ; coefficient of variation of elastic modulus, COV_E ) under the Monte Carlo simulation (MCS) framework. The probability density function (PDF) plots of the probabilistic dynamic settlement are also produced for a more accurate representation of the exceedance probability. The findings indicate that the probabilistic dynamic settlement values of the system exceed the deterministic values. However, the probabilistic values approach the deterministic result for the lower values of COV_E , L_x = L_y , and higher values of L_z , assuming the other statistical parameters remain constant.

Development and Numerical Modelling of a Novel Tunnel Freezing Segment for Tunnel Construction

Jian Liu, Panpan Guo, Xian Li, Yong Liu, Yixian Wang, Zili Li — Mon, 06 Apr 2026 07:15:05 -0700

ABSTRACT

In shield tunnel construction, it is critical to stabilize water-bearing strata and prevent leakage in the portal zone when the shield machine arrives at the receiving shaft. Conventionally, cement-based reinforcement and artificial ground freezing (AGF) methods are employed to strengthen the portal zone and prevent seepage. However, challenges remain, as seepage can occur along the excavation gap between tunnel linings and the surrounding soil due to unreliable synchronous grouting or shield deviation. To address this issue, this study proposes a novel built-in freezing tunnel segment (FTS) system, in which freezing tubes are integrated into precast shield segments. The FTS enables adaptive and precise freezing of both the excavation gap grout and surrounding soil, forming a supplemental frozen wall to block groundwater leakage. Multi-method validation was conducted and the results show that the FTS-enhanced AGF system eliminates seepage risks in high-permeability strata: (1) In-situ experiments confirmed the FTS's freezing efficiency (reaching −14.3°C at 80 mm distance within 48 h); (2) Field implementation in Tianjin Metro Line 10 demonstrated effective seepage control, freezing the excavation gap below −13°C; and (3) A numerical thermo-mechanical numerical model, calibrated against experimental data and incorporating latent heat effects, accurately replicated ground thermal responses. This integrated approach provides an alternative to conventional AGF systems that employ external freezing tubes and enables precise ground freezing under challenging hydrogeological conditions.

Coupled Discrete–Continuum Modeling of Soil Arching and Failure Modes in Pipeline‐Affected Ground Subsidence

Rui‐Xiao Zhang, Xiang‐Sheng Chen, Dong Su, Daniel Dias, Hong‐Tao Li — Mon, 30 Mar 2026 06:16:19 -0700

ABSTRACT

Understanding soil arching and failure modes of ground subsidence above buried pipelines is crucial for developing effective mitigation strategies to reduce sinkhole hazards. Although previous studies have examined soil arching using discrete or continuum methods, the soil–pipeline interaction under localized subsidence remains insufficiently quantified. To address this gap, the present study employs a discrete–continuum coupled (DEM–FEM) trapdoor model, which was quantitatively validated against previous trapdoor tests. Using this validated framework, the influence of pipeline diameter (D) on the evolution of soil arching was systematically analyzed for five D/B ratios ranging from 0.5 to 1.5. The results reveal that increasing the pipeline diameter broadens the disturbed zone and induces three distinct soil-arching evolution patterns: closure type, parallel open-ended type, and divergent open-ended type. A critical transition occurs at D/B = 1.0, corresponding to the minimum soil-arching ratio, beyond which arching efficiency improves. Larger trapdoor displacements reduce the magnitude and spatial extent of high-pressure zones, while varying D/B produces staged pressure redistribution and anisotropic stress transfer above the pipeline. Moreover, both the coordination number and fabric anisotropy analyses highlight microstructural degradation and directional instability with increasing pipeline diameter, revealing multiscale mechanisms governing stress redistribution and soil–structure interaction that have not been previously reported in trapdoor studies.

An Analytical Method to Estimate Hydrogeological Parameters of Nonlinear Consolidating Aquitards Under Generalized Complex Stress Boundaries

Ruizhe Wang, Zhaofeng Li, Qiang Zhang, Mo Xu, Hao Li, Jie Feng — Mon, 30 Mar 2026 06:11:55 -0700

ABSTRACT

Due to overlying loads or groundwater extraction, the boundary stresses of in-situ aquitards are complex and variable. Consequently, the consolidation deformation caused thereby makes it challenging to accurately determine hydrogeological parameters and predict deformation using traditional methods. Complex stress boundaries impose a significant computational burden on the estimation of hydrogeological parameters. To simplify the computational complexity, this study proposes two generalization methods for complex stress boundaries: multistage constant and multistage linear loads. Based on these two methods, analytical solutions for the nonlinear consolidation deformation rate and magnitude of aquitards are derived. Through dimensionless analysis of the deformation rate, a new type-curve fitting method is proposed for estimating hydrogeological parameters; parameter inversion results are obtained by fitting the analytical model with laboratory measured data. Finally, by comparing the measured data with the predicted curve of subsequent deformation based on the inversion results, the results exhibit a good degree of fitting. The results show that the hydrogeological parameters estimated by the two generalization methods and corresponding analytical solutions proposed in this study exhibit good accuracy in predicting deformations under subsequent loading stages, directly verifying the rationality of the two generalizations and the accuracy of the analytical solutions. The proposed analytical approach enhances our understanding of the nonlinear consolidation behavior of aquitards, contributes to the development of consolidation theory, and provides practical guidance for engineering applications.

Experimental Characterization and Hybrid LSTM‐RF Modeling of Time‐Dependent Interlayer Behavior in Mass Concrete Under Extreme Multi‐Physical Environments

Qingyang Ren, Hang Song, Bin Chen, Songqiang Xiao, Yanping Jia, Senlin Gao — Fri, 27 Mar 2026 00:55:21 -0700

ABSTRACT

Addressing the unclear mechanisms and insufficient prediction accuracy regarding the effects of extreme weather on the interlayer performance of mass concrete in Northwest China, this study proposes a novel framework for interlayer performance prediction and risk early warning, integrating multi-condition physical experiments with machine learning methods. The research simulates five typical extreme environmental conditions (high temperature, strong wind, rapid cooling, high temperature with strong wind, and cold wave with strong wind), and systematically quantifies the influence of various interlayer treatment measures (natural curing, thermal insulation covering, artificial grooves, and incorporation of PVA fibers) on the time-varying characteristics of concrete moisture content, penetration resistance development, splitting tensile strength, and crack resistance. Experimental results indicate that extreme compound conditions lead to a maximum reduction of 62.8% in interlayer splitting strength, with the combined effect of cold wave and strong wind being the most significant. The synergistic use of thermal insulation blankets and PVA fibers can achieve a strength recovery rate of up to 85.3%. Based on multi-source experimental data features, an LSTM-RF hybrid prediction model was constructed, where the long short-term memory (LSTM) network specifically processes the time-series features of moisture content and penetration resistance (prediction R ² > 0.92). The established “physical experiment–digital modeling” dual-driven approach provides a quantifiable decision-making basis for concrete construction in extreme environments.

Mechanisms and Stability of Adhesion‐Controlled Arching in Granular Materials

Wed, 25 Mar 2026 08:11:30 -0700

ABSTRACT

Arching in granular materials is a general phenomenon that exists in different domains of engineering such as underground excavations and particle flow in silos and hoppers. However, the arching effect in adhesive granular systems, which is common in practice, remains insufficiently understood. This study investigates the influence of particle adhesion on the evolution of the arching effect through discrete element method (DEM) trapdoor simulations. A surface energy-based adhesive interaction model was incorporated to represent varying adhesion strengths between particles. The results reveal three distinct arching patterns termed as progressive arching, structural arch, and beam-arching patterns, corresponding to a transition from friction-dominated to adhesion-controlled arching mechanisms as particle adhesion increases. With higher adhesion, deformation becomes increasingly constrained, stress concentration intensifies, and volumetric changes are suppressed. Increasing burial depth further amplifies stress redistribution within stationary zones and demands stronger adhesion for stable arching formation. Microscopically, particle adhesion enhances the continuity and anisotropy of contact force chains while reducing porosity evolution, resulting in a more persistent load-bearing arching. These findings provide a multiscale understanding of how adhesion modifies the stability and stress-transfer mechanisms of the arching effect, offering valuable insights for predicting deformation, optimizing ground reinforcement, as well as mitigating clogging in particulate-handling processes.

A Moisture‐Insensitive Mechanical Index for Intelligent Soil Compaction: Theory, Development, and Field Validation

Wed, 25 Mar 2026 08:03:55 -0700

ABSTRACT

In this study, a new intelligent compaction (IC) mechanical index, intelligent compaction vibration modulus E _ICV, was established by considering the influence of the subgrade moisture content. The field test was designed with varying moisture content sections to investigate the influence of moisture content on the E _ICV and compaction meter value (CMV). The results suggest that the E _ICV had better performance in evaluating the compaction quality of the subgrade than the CMV. It may be due to the similar trend of E _ICV and in-situ test results with the change of moisture content, while the CMV was adverse. Then, E _ICV and CMV were performed to regression analyses with the in-situ test results collected in the respective moisture content sections. The correlation of the in-situ test results with both E _ICV and CMV was strengthened compared with ignoring the influence of moisture content. It suggested that the different IC control standards for different moisture content ranges should be applied, rather than using a single standard in IC technology. Based on it, an IC project verification was conducted to validate the robustness of E _ICV by comparing it with other intelligent compaction measurement values (ICMVs). The results demonstrate that E _ICV has a stronger ability to reflect the compaction quality of subgrade compared with other ICMVs due to a better mechanical basis and considering the influence of moisture content difference. This study is conducive to improving the accuracy of IC evaluation and promoting the application of IC technology in subgrade construction.

Analytical Solution for Longitudinal Seismic Responses of Pipelines and Tunnels Crossing Soft‐Hard Rock Strata Based on Double‐Beam Model

Thu, 04 Dec 2025 00:00:00 -0800

ABSTRACT

Buried pipelines are susceptible to earthquake-induced damage when crossing soft-hard rock strata in high-intensity seismic regions. In mitigation, pipelines are usually installed within tunnels and buried under backfill materials. The existing seismic calculation method for pipelines does not consider the effects of tunnels. In this study, the pipeline-tunnel system crossing soft-hard rock strata is longitudinally simplified to an elastic foundation double-beam. Green's function is employed to derive the analytical solution for the longitudinal seismic response of the pipeline-tunnel system, whose validity is verified through numerical models and literature data. A parametric analysis is conducted through the control variable method. As the elastic modulus ratio between the hard and soft rocks increases, the peak internal forces of the pipeline and tunnel near the interface increase significantly. Specifically, the peak bending moments display a double-peak pattern, while the peak shear forces present a single-peak one. With the increase in the lining elastic modulus and thickness, the peak internal forces of the pipeline near the interface decrease, while those of the tunnel increase significantly. The peak internal forces of the pipeline increase sharply with the pipeline thickness, whereas those of the tunnel are hardly affected. The shaking table test results demonstrate that the tunnel crossing the interface sustained more severe damage than that in other segments, with oblique shear cracks appearing. This indicates that the sudden increase of the shear forces near the interface is one of the vital reasons for the structural damage, which verifies the rationality of the analytical solution.