Distinct Element Method Simulation of Rock Creep Behaviour

Rock creep behavior is an essential factor of many geotechnical projects, such as dam foundations, tunnels, rock-bolt or rock-socketed piles. Creep is a progressive deformation that many materials exhibit under a state of constant homogeneous stress. In the last decades, several laboratory creep tests have been conducted to study the creep behaviour of different types of intact or fractured rock samples. Based on experimental data several creep models have been proposed to reproduce the creep behaviour observed empirically; however, these approaches often do not reproduce all phases of creep behaviour satisfactorily. In this work, a numerical model in PFC2D is employed to simulate a compression multistage creep test on slate rock using an implementation of the rate process theory proposed by Kuhn and Mitchell (1992) and a hybrid contact model –with the Linear Model and the Flat Joint Contact Model– to represent the behaviour of contacts between particles. The numerical results are compared with experimental data of a uniaxial compression multistage creep test conducted on slate. DEM2D results suggest that the rate process theory is able to reproduce all phases of creep behaviour on slate, particularly the tertiary creep