DEM studies on the effect of particle breakage on the critical state behaviours of granular soils under undrained shear conditions

Abstract

A number of discrete element analyses of undrained triaxial shear tests on crushable assemblies are performed using 3-dimensional particle flow code (PFC3D). The undrained shear of the samples is simulated by assigning different velocities at the boundaries to control the constant volume of the samples during the shear. Particle breakage is studied using the octahedral shear stress breakage criterion and the fragment spawning mode satisfying an Apollonian sphere packing. The microparameters of the soils are obtained by simulating the test results reported on a Nansha calcareous sand. The effects of particle breakage and drainage condition on the critical state behaviours of the sand are intensively examined. It is found that particle breakage and drainage condition do not affect the slope of the critical state p′−q line. In the ecs−(p′cs/pa)0.7 space, the critical state line translates downward and rotates clockwise when particle breakage is considered, whilst drainage condition does not affect the critical state line. The intrinsic macro–micro correlations underlying the critical state behaviours are explored by analysing the evolution of representative micromechanical indicators such as coordination number, redundancy ratio, and fabric and force anisotropies.

Constitutive Model with Three State Variables for Coral Sand Considering the Effect of Particle Breakage

“…It should be recognized that granular soils, including coral sand, display notable state-dependent behaviour (Li and Dafalias, 2000;Xiao et al, 2019;Shi et al, 2022;Trong and Mamoru, 2023). Additionally, the properties are influenced by three primary state variables: gradation, void ratio, and confining pressures (Ciantia et al, 2019;Lv et al, 2019;Peng et al, 2020;Tengattini et al, 2016;Xiao et al, 2017aXiao et al, & 2017bWang et al, 2024).…”

Effects of particle breakage on the mechanical characteristics of geogrid-reinforced granular soils under triaxial shear: A DEM investigation

“…Especially for calcareous sand, DEM can well simulate its particle breakage characteristics to truly reflect the relationship between its macro behaviors and micro fabrics [20][21][22][23]. In DEM, particle crushing has generally been modelled via different solutions: replacing broken grains with smaller fragments (i.e., fragment replacement method, FRM) [24][25][26][27][28][29]; or using agglomerates-groups of bonded particles with finite bond strengths (i.e., bonded particle method, BPM) [21,30,31]; or coupling by finite element mesh of tomography image data (i.e., finite-discrete element method, FDEM) [32][33][34][35]. For example, Li et al (2017) [36] adopted BPM to investigate the features of particle breakage for cemented sand with different bond strengths.…”

Study on Macro-Meso Deformation Law and Acoustic Emission Characteristics of Granular Gangue under Different Loading Rates

“…The gangue is widely used as backfill material, and its deformation characteristics under the loading effect of overburden directly affect the rock stability control effect [4,5]. Therefore, it is important to study the deformation characteristics of the coal gangue during load-bearing compression to improve the load-bearing capacity of the backfill body [6,7].…”