This paper proposes a regularized smoothed particle hydrodynamics (SPH) scheme to solve the problems of tensile instability and stress noise in large‐deformation soil–structure interaction. Particle shifting and stress regularization are combined to maintain uniform stresses and particle distributions. A generalized frictional boundary condition is presented to model soil–structure interfaces with abitrary friction coefficients. A modified particle shifting technique is developed to regularize particles near the frictional boundaries. Furthermore, GPU acceleration algorithm is adopted to improve the efficiency. The proposed scheme is compared with the conventional SPH methods using numerical examples, including the collapse of three‐dimensional granular column, the collapse of the cohesive soil, and pipe penetrates into soft clay. The comparison indicates that the proposed regularized SPH model can give highly accurate results for large‐deformation soil–structure interaction problems with arbitrary friction coefficient.

We propose a smoothed particle hydrodynamics (SPH) model bridging the gap between solid‐ and fluid‐like behaviour observed in granular materials. The key innovation of the proposed approach lies in the decomposition of the stress gradient into rate‐independent and rate‐dependent parts, which are governed by the hypoplastic and constitutive relations, respectively. By using the proposed approach, we successfully capture the transition between solid‐ and fluid‐like flow regimes in granular materials. The proposed SPH scheme is rigorously validated through the examination of various boundary value problems, including the collapse of a granular column, Taylor–Couette flow, and silo flow.

Understanding the dynamic evolution of pore and fracture structure (PFS) in coal under mining disturbance is essential for safe coal extraction. In this study, coal specimens collected from the Dongqu Mine, Taiyuan, Shanxi Province, China, were subjected to stepwise cyclic confining pressure loading–unloading tests using a triaxial in situ nuclear magnetic resonance (NMR) system. Based on T₂ spectrum measurements, the real-time evolution of PFS, stress–strain response, permeability-related behavior, average pore diameter, and fractal characteristics were systematically investigated. The results show that irreversible damage developed in the coal specimens during cyclic confining pressure loading–unloading. With increasing cycle number, the load-bearing capacity gradually decreased, internal damage intensified, and pore expansion and coalescence became more pronounced. Seepage pore porosity showed an overall increasing trend, indicating a gradual enhancement of inferred permeability. Therefore, seepage pore porosity can be used as an effective indicator for evaluating permeability-related evolution in coal. During both loading and unloading stages, the relative volumes of small pores (SP), medium pores (MP), and large pores and fractures (LPF) continued to increase, whereas their average pore diameters fluctuated. This indicates that pore volume growth was controlled not only by the enlargement or shrinkage of pre-existing pores but also by new PFS generation. Fractal analysis showed that the fractal dimensions of MP, LPF, and total pores exhibited clear scale-dependent evolution, whereas the calculated SP fractal dimensions were lower than 2 and were therefore not suitable for pore-surface fractal interpretation. Among the valid pore systems, LPF exhibited the highest fractal dimension, indicating that LPF dominate the structural complexity of coal. These findings provide new insight into the fractal evolution of unloading-induced PFS damage and offer theoretical support for mitigating gas outburst and water inrush hazards during coal mining.