The weakening of inter-particle friction and its effect on mechanical behaviors of granular soils

This paper describes a numerical study examining the effect of weakening of inter-particle friction on granular soil responses. A bi-linear friction weakening model is proposed to describe the reduction of inter-particle friction with the increase of contact normal force. Through a series of drained triaxial loading tests from 3D DEM simulations, it is observed that the influence of friction weakening is quite limited on macro-mechanical behaviors for granular packing under a low confining stress. With the increase of confining stress, the influence of friction weakening gradually becomes significant. Samples embedded with friction weakening model exhibit relative lower peak strength and less dilatancy, compared with samples with constant inter-particle friction. From micromechanical perspective, samples embedded with friction weakening model has lower particle friction, which in turn lead to higher contact sliding ratio and lower tangential contact force for the packing. Higher sliding ratio implies more particle movement and less dilatancy of the packing. The lower tangential contact force at the microscale matches well with the lower peak strength at the macroscale. At critical state, the strength for samples with different friction models is concisely explained by analyzing the critical void ratio and tangential contact force distribution.

Automated summary

This paper investigates the effect of weakening of inter-particle friction on granular soil responses. The study shows that the influence of friction weakening is limited under low confining stress but becomes significant with increasing confining stress. From a micromechanical perspective, samples with friction weakening model have lower particle friction, resulting in higher contact sliding ratio and lower tangential contact force, which leads to lower peak strength at the macroscale.