CONSTITUTIVE MODELS FOR ROCK DISCONTINUITIES WITH DILATANCY AND SURFACE DEGRADATION

A physically motivated constitutive law for the behavior of geologic discontinuities with dilatancy and contact surface degradation (damage) is presented. In the formulation of the law, the paper distinguishes between macroscopic and microscopic features of the contact surface. Through macroscopic considerations, an incremental constitutive law is derived which is applicable to a large class of contact-friction problems. By idealizing the microstructure to consist of interlocking asperity surfaces, the constitutive equations are specialized for the description of rock joints including effects such as dilatancy, asperity surface degradation and bulking. Several examples are considered demonstrating the law's behavior and agreement with experimental data. The incremental form of the equations that are derived are amenable to implementation in numerical procedures such as finite element and discrete element (rigid block) computer programs.