New shear strength criteria for rock joints taking into account anisotropy of surface morphology

Abstract : Three new peak shear stress criteria were proposed to predict the Variation of shear strength with normal stress for dilatant (irregular and regular surfaces) and non-dilatant to slightly dilatant (planar rough surfaces or regularly undulated surfaces ) rock joints under both constant normal stress (CNS) and constant normal stiffness (CNK) loading. The planar rough surfaces exhibit an isotropic nature whereas the undulated surfaces are anisotropic. These models take into account the progressive degradation of surface roughness during the course of monotonous or cyclic shearing. The third proposed model is a generalized new shear strength criterion which predict successfully the shear strength behaviour of rock joints under CNS and CNK loading.