Mechanical Behavior of Rock-Like Specimens with Hidden Smooth Joints under Triaxial Compression

Abstract

The mechanical behavior of rock mass is strongly influenced by internal joints. To investigate the effect of hidden joints on the strength and deformation behavior of rock mass, a series of triaxial compression tests was carried out using specimens made from rock-like material. In the experiments, a self-designed pouring apparatus was used to prepare specimens with hidden smooth joints at a given inclination angle. Based on the experimental results of axial stress–axial strain curves, the effect of joint inclination angle and confining pressure on the mechanical behavior of the jointed specimens was analyzed. Four failure modes, which are related to joint inclination angle, were identified. An anisotropic effect parameter was proposed to reflect the degree of strength anisotropy affected by joint angle and confining pressure. It was found that the strength anisotropy decreases with the increase of confining pressure. Finally, the Mohr–Coulomb and the Hoek–Brown failure criteria were applied to describe the strength of the jointed specimens. It was found that the strength parameters of the two failure criteria are closely related to joint inclination angle. The Hoek–Brown failure criterion described the strength envelope of the jointed specimens better than the Mohr-Coulomb failure criterion.