Modeling time-dependent deformation behavior of brittle rock using grain-based stress corrosion method

Abstract

This research presents a grain-based stress corrosion model to simulate time-dependent failure of brittle rock. Time-dependent deformation of rock is considered as the manifestation of stress corrosion that may occur inside grains and on grain boundaries. A damage-rate law is adopted and modified to describe continuous degradations of parallel-bond diameters and contact properties in the stress corrosion process. A detailed numerical scheme with self-adaptive determination of time step is used to simulate the time-dependent deformation behavior of rock. The results show that both the short-term mechanical properties and the fatigue test results of Lac du Bonnet granite can be reproduced by the proposed method. In addition, compared with the original parallel-bond stress corrosion method, the modified grain-based stress corrosion method predicts the failure time of rock better under low driving-stress ratios. With the increase of the driving-stress ratio, the failure time of the numerical specimen decreases, and the creep curves tend to have a stair-stepping shape. The numerical simulation results show that an increase of 15 MPa confining pressure under a driving-stress ratio of 0.6 can lengthen the failure time of the rock from 139 days to 11 years.