A three-dimensional damage-based contact element model for simulating the interfacial behaviors of rocks and its validation and applications

Abstract

To describe the mechanical behavior of interfaces existing in rocks, a three-dimensional contact element model with a certain thickness was proposed that could simultaneously consider the heterogeneity, damage evolution and state variation of interfaces. The Weibull distribution function was employed to describe the rock heterogeneity. The damage evolution of the contact element was analyzed by using the equivalent damage method. Two criteria—the Mohr–Coulomb criterion and the maximum tensile stress criterion—were employed to assess the damage occurrence. Once the element was identified as being completely damaged, the state variation of the contact element was determined. Three types of element states—contact without sliding, contact with sliding, and separation—were taken into consideration. The model was then implemented and programmed into the finite element method and validated with experimental measurements and theoretical solutions for three classical rock mechanical problems, including one static problem (i.e., a direct shear test) and two dynamic problems (the seismic responses of rock joints and split-Hopkinson pressure bar tests), in an attempt to examine the applicability of the proposed contact element model. The results demonstrated that the contact element model can effectively model the rock interfacial problems and can therefore help solve problems in discontinuous rock masses.