Modelling jointed rock mass as a continuum with an embedded cohesive-frictional model

Abstract

The mechanical and hydraulic properties of a jointed rock mass are strongly affected by the characteristics of joints within the intact rock mass. In this study, a constitutive model for jointed rock masses is developed by incorporating the contributions of both the joint and its surrounding rock mass. The behaviour of the joint is represented by a new coupled damage-plasticity cohesive-frictional model taking into account its dilation evolution and the reduction of both strength and stiffness, while the surrounding rock behaviour is assumed to behave elastically. The interactions between the joint and the surrounding rock are described by a set of kinematic enhancements and internal equilibrium equations across the interface of the joint. The formulation of the proposed model is presented along with its implementation algorithms and validation with experimental data. The enhanced kinematics facilitates the incorporation of both behaviour and orientation of the joint, together with the size and behaviour of the surrounding rock, allowing capturing key characteristics of jointed rock mass responses under mixed-mode loading conditions at different spatial scales.