This study introduces a coupled peridynamics (PD) and smoothed particle hydrodynamics (SPH) model to handle the complex physical processes in concrete dam structures subjected to near-field underwater explosions. A robust coupling algorithm is applied to ensure accurate data exchange between PD and SPH domains, enabling the simulation of fluid-structure interactions. To account for the material behavior under high strain rates, a rate- dependent concrete model is integrated into the PD-SPH framework. The developed PD-SPH model is validated through simulations of centrifugal model tests, with results benchmarked against experimental findings and finite element method (FEM) predictions. The simulation captures key damage features, including horizontal tensile cracking at the dam head and an oblique penetrating crack in the dam body, forming an angle of approximately 17 degrees relative to the horizontal. Velocity and strain responses at critical monitoring points demonstrate strong agreement with FEM results, showcasing the model's capability in accurately predicting the structural responses and failure of concrete dams caused by underwater explosions. To the best of the authors' knowledge, research applying a coupled PD-SPH model to concrete structures under blast loading is still rare, particularly when considering the entire physical process, from explosive detonation to structural failure, accounting for fluid-structure interactions.

Polyurethane foam, when used as a compressible layer in deep soft rock tunnels, offers a feasible solution to reduce the support pressure on the secondary lining. The foam spraying method using sprayed polyurethane material is convenient for engineering applications; however, the compressive behaviour and feasibility of sprayed polyurethane material as a compressible layer remain unclear. To address this gap, this study conducts uniaxial compression tests and scanning electron microscope (SEM) tests to investigate the compressive behaviour of the rigid foams fabricated from a self-developed polyurethane spray material. A peridynamics model for the composite lining with a polyurethane compressible layer is then established. After validating the proposed method by comparison with two tests, a parametric study is carried out to investigate the damage evolution of the composite lining with a polyurethane compressible layer under various combinations of large deformations and compressible layer parameters. The results indicate that the polyurethane compressible layer effectively reduces the radial deformation and damage index of the secondary lining while increasing the damage susceptibility of the primary lining. The thickness of the polyurethane compressible layer significantly influences the prevention effect of large deformation-induced damage to the secondary lining within the density range of 50-100 kg/m3. In accordance with the experimental and simulation results, a simple, yet reasonable and convenient approach for determining the key parameters of the polyurethane compressible layer is proposed, along with a classification scheme for the parameters of the polyurethane compressible layer. (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/).

Soil desiccation cracking, a natural phenomenon involving the complex interaction of multi-physical fields, significantly weakens the mechanical and hydraulic properties of soil, potentially leading to natural hazards. This study proposes a coupled thermo-hygro-mechanical peridynamic (PD) model to investigate the mechanical responses and fracture behaviors in saturated soils due to moisture evaporation and heat transfer. Specifically, the temperature-dependent moisture diffusion and moisture-dependent heat conduction equations are nonlocally reformulated using peridynamic differential operators (PDDO). The constitutive model incorporates the spatial attenuation of nonlocal interactions and the effects of moisture and temperature in the bond-based peridynamic framework. Utilizing a hybrid explicit-implicit solution strategy, the model can effectively capture soil strip detachment, cracking, and curling. The model is also employed to explore moisture transmission mechanisms, evaluate the effects of temperature and thickness on crack morphology, and reveal the relationship between stress, strain evolution, and crack propagation. Furthermore, the model incorporates the reference evapotranspiration formula, which can account for environmental factors such as solar radiation, ambient temperature, relative humidity, and wind speed. Therefore, this expands the scope of model applicability and enables the simulation of soil desiccation cracking under natural conditions.

The current study presents superposition-based concurrent multiscale approaches for porodynamics, capable of capturing related physical phenomena, such as soil liquefaction and dynamic hydraulic fracture branching, across different spatial length scales. Two scenarios are considered: superposition of finite element discretizations with varying mesh densities, and superposition of peridynamics (PD) and finite element method (FEM) to handle discontinuities like strain localization and cracks. The approach decomposes the acceleration and the rate of change in pore water pressure into subdomain solutions approximated by different models, allowing high-fidelity models to be used locally in regions of interest, such as crack tips or shear bands, without neglecting the far-field influence represented by low-fidelity models. The coupled stiffness, mass, compressibility, permeability, and damping matrices were derived based on the superposition-based current multiscale framework. The proposed FEM-FEM porodynamic coupling approach was validated against analytical or numerical solutions for one- and two-dimensional dynamic consolidation problems. The PD-FEM porodynamic coupling model was applied to scenarios like soil liquefaction-induced shear strain accumulation near a low-permeability interlayer in a layered deposit and dynamic hydraulic fracturing branching. It has been shown that the coupled porodynamic model offers modeling flexibility and efficiency by taking advantage of FEM in modeling complex domains and the PD ability to resolve discontinuities.

Rainfall is a pivotal factor resulting in the cause of slope instability. The traditional finite element method often fails to converge when dealing with the strongly nonlinear fluid-solid coupling problems, making it impossible to fully analyze the sliding process under the state of slope instability. Therefore, this paper uses the coupling of peridynamics (PD) and the finite element method (FEM) to propose a data exchange mode between the seepage field and the deformation field. The influencing factors of fine particle erosion during rainfall are further considered. According to the damage mechanism of the slope sliding process to the original structure of the soil, a modified erosion constitutive relationship is proposed, which takes into account the destructive effect of plastic deformation on coarse particles. Then, the influence of rainfall duration, rainfall intensity, erosion, and initial saturated permeability coefficient on slope stability was simulated and analyzed. This paper provides a novel concept for slope stability analysis and safety evaluation under rainfall conditions.

Twin tunnel excavations can seriously affect the integrity of buried pipelines. In this investigation, centrifuge model tests and numerical simulations were carried out to study the brittle damage of buried pipelines induced by side-by-side twin tunneling. In the numerical model, the pipelines were simulated as peridynamics (PD) shell structures, the surrounding soil was represented as a series of independent Winkler springs, and the modified Gaussian curve was incorporated as displacement-controlled boundary conditions on the springs to simulate the sequential excavation of side-by-side twin tunneling. The effectiveness of the numerical method was assessed by comparing with the centrifuge model test results. Due to the interactions of two tunnels, the fracture characteristics were more complex for twin tunneling compared with the case of single tunneling. The fracturing point induced by the second tunneling could deviate from the second tunnel centerline. The first tunneling without inducing damage can suppress the damage initiation and propagation in the pipeline under the second tunneling. A pipeline with a smaller diameter and a higher critical energy release rate in sandy soils with a lower friction angle and a shallower burial depth has a higher capacity to resist damage under twin tunneling, showing a greater initial fracture angle.

The concept of critical state has been a cornerstone of modern critical state soil mechanics. It remains inconclusive how grain crushing affects critical state behavior in crushable granular sand. A multiscale computational approach is employed in this study to simulate the shearing behavior of crushable granular sand at critical state. Grain crushing is rigorously considered by preserving the co-evolutions of grain size and shape in the simulation of the shearing process. Systematic simulations on specimens with varying initial states and loading paths show unique characteristics of critical state for crushable granular sand in terms of critical state stress ratio, void ratio, breakage index, and shape descriptors which are independent of stress path and initial conditions. To further understand the deformation mechanisms of crushable sand at critical state, the volumetric strain is decomposed into three components due respectively to grain size reduction, the interlocking of irregular shaped grains generated by crushing, and inter-particle friction. Competing mechanisms among the three strain components are quantitatively analyzed and discussed. Initial void ratio and stress levels are found to play a prominent role in shaping the critical state deformation of crushable sand and such impact may be gauged through the fraction of grains that experience crushing.