Mesh-free methods, such as the Smooth Particle Hydrodynamics (SPH) method, have recently been successfully developed to model the entire wetting-induced slope collapse process, such as rainfall-induced landslides, from the onset to complete failure. However, the latest SPH developments still lack an advanced unsaturated constitutive model capable of capturing complex soil behaviour responses to wetting. This limitation reduces their ability to provide detailed insights into the failure processes and to correctly capture the complex behaviours of unsaturated soils. This paper addresses this research gap by incorporating an advanced unsaturated constitutive model for clay and sand (CASM-X) into a recently proposed fully coupled seepage flow-deformation SPH framework to simulate a field-scale wetting-induced slope collapse test. The CASM-X model is based on the unified critical state constitutive model for clay and sand (CASM) and incorporates a void-dependent water retention curve and a modified suction-dependent compression index law, enabling the accurate prediction various unsaturated soil behaviours. The integration of the proposed CASM-X model in the fully coupled flow deformation SPH framework enables the successful prediction of a field-scale wetting-induced slope collapse test, providing insights into slope failure mechanisms from initiation to post-failure responses.

Deep excavations in silt strata can lead to large deformation problems, posing risks to both the excavation and adjacent structures. This study combines field monitoring with numerical simulation to investigate the underlying mechanisms and key aspects associated with large deformation problems induced by deep excavation in silt strata in Shenzhen, China. The monitoring results reveal that, due to the weak property and creep effect of the silt strata, the maximum wall deflection in the first excavated (Section 1) exceeds its controlled value at more than 93% of measurement points, reaching a peak value of 137.46 mm. Notably, the deformation exhibits prolonged development characteristics, with the diaphragm wall deflections contributing to 39% of the overall deformation magnitude during the construction of the base slab. Subsequently, numerical simulations are carried out to analyze and assess the primary factors influencing excavation-induced deformations, following the observation of large deformations. The simulations indicate that the low strength of the silt soil is a pivotal factor that results in significant deformations. Furthermore, the flexural stiffness of the diaphragm walls exerts a notable influence on the development of deformations. To address these concerns, an optimization study of potential treatment measures was performed during the subsequent excavation of Section 2. The combined treatment approach, which comprises the reinforcement of the silt layer within the excavation and the increase in the thickness of the diaphragm walls, has been demonstrated to offer an economically superior solution for the handling of thick silt strata. This approach has the effect of reducing the lateral wall displacement by 83.1% and the ground settlement by 70.8%, thereby ensuring the safe construction of the deep excavation. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

The paper presents a refined implicit two-phase coupled Material Point Method (MPM) designed to model poromechanics problems under static and dynamic conditions with stability and robustness. The key variables considered are the displacement and pore water pressure. To improve computational efficiency, we incorporate the Finite Difference Method (FDM) to solve pore pressure, stored at the center of the background grid where the material points reside. The proposed hydromechanical MPM cannot only effectively addresses pore pressure oscillation, particularly evident in nearly incompressible fluids-a common challenge with Galerkin interpolation, but also decreases the degrees of freedom of the system equations during the iteration process. Validation against analytical solutions and various numerical methods, encompassing 1D and 2D plane-strain poromechanical problems involving elastic and elastoplastic mechanical behavior, underscores the method's resilience and precision. The proposed MPM approach proves adept at simulating both quasi-static and dynamic saturated porous media with significant deformation.

Recently, bio-inspired technology utilizing the anisotropy of friction between structure-soil has garnered significant attention. In particular, new pile designs not only enhance shaft friction but also gain prominence by reducing the use of cement, which has traditionally been a key material in ground treatment and improvement. Previous studies have quantitatively verified the increase in interface shear resistance through direct shear tests and cone penetration experiments. However, conventional finite element analysis methods face limitations in analyzing the shaft friction behavior between piles with scale and the surrounding soil. In this study, the Coupled Eulerian-Lagrangian (CEL) technique, a large deformation analysis method built-in ABAQUS, is employed to simulate the penetration of cone with textured shaft. Numerical analyses are conducted to investigate changes in cone penetration resistance according to the geometric characteristics of the surface scale. To minimize numerical errors occurring in the cone and surrounding soil meshes, a three-dimensional generalized mesh is proposed for the cone and its surrounding elements. A total of 13 cases, comprising seven different cone designs and two penetration direction conditions, are analyzed. The results showed that under the same penetration load, penetration depth decreased as the scale height increased, the scale length narrowed, and the scale tapered in height.

Since deformable granular materials with arbitrary morphologies constructed by different dilated non-spherical models in complex structures remain challenging for numerical simulations using the discrete element method (DEM), a unified Minkowski sum model was proposed for calculating collision forces and large deformations of arbitrarily shaped granular materials and structures. In this model, dilated superquadric equations, dilated spherical harmonic functions, and dilated polyhedrons were developed to construct arbitrarily shaped particles, and Fibonacci and automatic mesh simplification algorithms were established to determine the surface meshes of the particles with controlled accuracy. Subsequently, the Minkowski sum model based on chain-linked meshes and granular skeletons was proposed to calculate collision forces and large deformations of rigid and deformable granular materials. To investigate the conservation, accuracy, and robustness of the proposed model, six sets of numerical examples were conducted and compared with the theoretical and finite element results, which included the static analysis of a deformable granular skeleton, the mechanical analysis of a single deformable structure, a single deformable particle impacting a rigid wall, the collision between two rigid and deformable particles, the accumulation of multiple rigid particles on a deformable structure, and compression of multiple deformable particles within a deformable structure. The corresponding numerical results are in good agreement with the theoretical and finite element results, which verifies that the present DEM model can accurately predict the large deformation characteristics of different dilated DEM models and can be extensively applied to the dynamic flows and deformation behaviors of arbitrarily shaped granular materials involving multiple DEM models in deformable structures.

Due to geological processes such as sedimentation, tectonic movement, and backfilling, natural soil often exhibits characteristics of rotated anisotropy. Recent studies have shown the significant impact of rotated anisotropy on slope stability. However, little research has explored how this rotated anisotropy affects the large deformations occurring after slope failure. Therefore, this study integrates rotated random field theory with smoothed particle hydrodynamics (SPH) to investigate its influence on post-failure slope behavior. Focusing on a typical slope scenario, this research utilizes graphics processing unit (GPU)-accelerated covariance matrix decomposition (CMD) method to create rotated anisotropy random fields and applies the SPH framework for analysis. It examines the influence of rotated anisotropy angles and the cross-correlation between cohesion and internal friction angle on landslides. The results indicate that the rotational anisotropy of the slope significantly influences post-failure behavior. When the rotation angle is close to the slope surface, it tends to amplify both the magnitude and variability of slope failure. Furthermore, the study evaluates the efficiency of generating these random fields and emphasizes the substantial computational speed improvements achieved with GPU acceleration. These findings offer a robust approach for probabilistic analysis of slope large deformations considering rotated anisotropy. They provide a theoretical foundation for accurately assessing the risk of slope collapse, holding significant practical implications for geotechnical engineering.

Seepage-induced backward erosion is a complex and significant issue in geotechnical engineering that threatens the stability of infrastructure. Numerical prediction of the full development of backward erosion, pipe formation and induced failure remains challenging. For the first time, this study addresses this issue by modifying a recently developed five-phase smoothed particle hydrodynamics (SPH) erosion framework. Full development of backward erosion was subsequently analysed in a rigid flume test and a field-scale backward erosion-induced levee failure test. The seepage and erosion analysis provided results consistent with experimental data, including pore water pressure evolution, pipe length and water flux at the exit, demonstrating the good performance of the proposed numerical approach. Key factors influencing backward erosion, such as anisotropic flow and critical hydraulic gradient, are also investigated through a parametric study conducted with the rigid flume test. The results provide a better understanding of the mechanism of backward erosion, pipe formation and the induced post-failure process.

Permeable pipe piles accelerate the bearing capacity of the pile foundation by releasing the excess pore water pressure (EPWP) of the soil around the pile through appropriate openings in the pile body. This study couples the Material Point Method (MPM) and the Finite Element Method (FEM) to establish a full-process model of pile driving and consolidation of permeable piles, and proposes a continuous drainage boundary condition that can reflect the plugging effect of permeable holes. The correctness of the model and boundary conditions are verified by comparison with experiments, and then the effects of soil properties, opening characteristics, and boundary permeability on the accelerated consolidation effect of permeable piles are analyzed. The results show that: the permeable pile with a permeable area ratio greater than 50% and a local opening ratio greater than 5% can save more than 60% of the consolidation time compared to conventional piles; the proposed boundary conditions can accurately describe the permeability of the permeable hole under the influence of plugging; in addition, the calculation formulae for the accelerated consolidation effect of permeable piles and the variation of continuous drainage boundary interface parameters with permeable area ratio are given, which can provide references for engineering design.

The pull-out capacity of plate anchor is significantly impacted by the embedment loss during keying, necessitating its prior estimation. The soil surrounding the anchor undergoes considerable disturbance during keying, but the soil softening induced by accumulated shear strains was neglected in almost all the existing numerical studies. In this paper, an elastic-perfectly plastic model with strain-softening was combined with the integraltype nonlocal method to overcome the mesh dependency in large deformation finite element simulations. The biaxial compression tests were simulated firstly and the keying process of strip anchors were reproduced by varying anchor width, thickness, loading eccentricity, undrained shear strength and sensitivity. It was observed that the ultimate embedment loss increased nearly linearly with soil sensitivity, a trend that was especially pronounced at lower loading eccentricity ratio. The generalized equations for evaluating the ultimate embedment loss were proposed and their reliabilities were verified by the existing centrifuge tests.

As the latest development and benchmark of a gravity installed anchor (GIA), the OMNI-Max anchor stands as a cutting-edge achievement and benchmark, finding increasingly widespread use within mooring systems due to its exceptional operational performance and adaptability. Notably, while investigations into the pullout capacity of OMNI-Max anchors have been conducted extensively in clay, the relevant studies are seldom observed in sand. Actually, the mechanical properties of sand are quite different from those of clay, and sand is also widely distributed in seabed soil. Full knowledge of OMNI-Max anchors not only in clay but also in sand is necessary to a wider application of the anchors. In the present work, the large deformation finite element (LDFE) method is adopted combined with the coupled Eulerian-Lagrangian (CEL) technique to study the end-bearing characteristics of the OMNI-Max anchor in sand seabeds. A bounding-surface plasticity model is taken as the constitutive model to capture the characteristics of sand. Through investigation and analysis, OMNI-Max anchors are closely related to the anchor embedment depth, the soil relative density, the anchor orientation, the loading angle and the bearing area, so the working conditions related to these five factors are designed and calculated. An explicit expression of the end-bearing capacity factor is finally derived to provide a simple and fast tool of evaluating the pullout capacity of the anchor in sand under multiple factors. Validation cases and orthogonal tests have confirmed the effectiveness and applicability of the explicit expression.