Discrete element simulation of fracture surface damage and gouge particle evolution in a a rock fracture segment

Abstract

The surface damage and evolution of gouge materials in rock fractures or faults undergoing shear can change fracture properties in terms of shear strength and dilation, fluid transmissivity and retardation for contaminants. In order to conceptually understand fracture surface damage and gouge behaviors in fracture voids, the particle mechanics models were used to simulate the process of gouge particle plowed off from fracture asperities and subsequently their evolution in a fracture segment undergoing shear. The results show that significant abrasion and damage occurred by wearing the contact asperities and cracking the fracture surfaces. Gouge particles behave in two different ways under low and high normal stresses, respectively. Under low normal stress, gouge particles mainly roll with the moving fracture walls, with little surface damage. Under high normal stress, gouge particles can be crushed into a few major pieces and a large number of minor comminuted particles, accompanied by more severe damage (abrasion and micro-cracking).