The friction-weakening cause by localized wear-induced damage and its effect on liquefaction resistance of sandy soil using DEM

Abstract

Localized wear-induced damage caused by stress concentration at the contact point can lead to the decrease of the frictional coefficient (μ) of sandy soil, further affecting the liquefaction resistance. In this study, a bi-linear the friction-weakening model is proposed to describe the decreasing trend of μ with the increase of normal contact force (fn). Through a series of undrained cyclic triaxial tests, the influence of localized wear-induced damage on the characteristics of cyclic liquefaction is investigated from both macroscopic and microscopic perspectives. The macroscopic results indicate that samples have weaker liquefaction resistance due to the friction-weakening. Under low confining pressure (P0), the influence of the friction-weakening on the liquefaction resistance is relatively limited. With the increase of P0, the decrease of liquefaction resistance gradually becomes significant. However, the effect of friction-weakening on the liquefaction resistance does not remain constant, but shows a decreasing trend with the accumulation of excess pore water pressure ratio (EPWPR). From the microscopic perspective, the reduction of liquefaction resistance can be explained by the coordination number (Z) and the contact sliding ratio. Although higher Z caused by the friction-weakening may lead to greater liquefaction resistance, higher sliding contact ratio have been found to weaken the liquefaction resistance, and its influence exceeds Z.