Influence of time-dependence on failure of echelon rock joints through a novel DEM model

Abstract

This article investigates the time-dependent influence on the shear failure behaviour of parallel rock joints in the echelon arrangement due to chemical weathering, which can be treated as a generalised time-dependency of the rock material. A time-dependent parameter α, identifying the accumulated relative mass removal of bonding material, has been implemented into a novel distinct element method bond contact model. This model is based on a series of mechanical test on bonded aluminium rods with different bond geometries. The numerical direct shear test results of echelon rock joints characterised by different values of α show that increasing time-dependent parameter α can lead to a lower crack initiation and peak stresses. This is accompanied by a growing ratio of the microscopic compressive–shear–torsional (CST) bond failure number of bond failures to the total number of failures, except for the case without weathering influence. High values of α render the material bridge a weaker part to be cut through, generating a large number of CST bond breakages along the central shear axis