Microscale Descriptors for Particle-Void Distribution and Jamming Transition in Pre- and Post-Liquefaction of Granular Soils

AbstractMicromechanical modeling provides significant insight into the fundamental mechanism of soil liquefaction. In this study, a series of undrained cyclic simple shear simulations were conducted by using discrete element method (DEM). The particle-scale information provided by DEM was used to quantify the local void distribution around particles. Two microscale descriptors, named as the shape-elongation descriptor (Ed) and the orientation-anisotropy descriptor (Ad), were proposed to quantify the overall anisotropy of local void distribution in the granular packing. Before initial liquefaction, the particle-void distribution remains to be globally isotropic for isotropically consolidated samples. An irreversible development of anisotropy in terms of Ed and Ad mainly occurs in the post-liquefaction stage. In addition, jamming transition of the liquefied soil is determined by using these descriptors because a unique hardening state line (HSL) is found in the Ed−Ad space that can differentiate a post-liquefaction flow state from a hardening or jamming state. Furthermore, large post-liquefaction flow strains are found to be closely correlated to the descriptors.