A multi-scale roughness shear joint model using wear theory

Abstract

Fracture is the weakest structure and dominates the shear strength of the natural rock mass. This structure potentially leads to many engineering hazards. Although various shear constitutive models have been developed previously their limitations have not been fully explained. Among them, there is an argument that the shear-off component added in the same manner with the basic sliding friction lacks physical meaning. Many models have been developed based on the lab-scale joint samples, thereby being less reliable when evaluating shear strength of field-scale joint. A new shear constitutive model incorporated with lab-scale has been developed in which the degradations of the irregularities are simulated based on the wear theory. Semi-empirical equations are proposed to estimate the wear coefficients to avoid the back-analyses of the experimental results in order to obtain input values. As different scaled roughness has different effects on both mechanical and hydraulic behaviours, multiscale roughness parameters are employed in the mechanical model. The proposed mechanical model potentially can be expanded to the development of the coupled hydromechanical model.