Anisotropic mechanical behaviour of columnar jointed rock masses subjected to cyclic loading: An experimental investigation

Abstract

In order to investigate the anisotropic mechanical behaviour of the columnar jointed rock masses (CJRM) under cyclic loading, triaxial cyclic loading-unloading tests are conducted on artificial CJRM specimens with a geological structure similar to the actual CJRM under the confining pressures of 5 MPa. In this work, particular attention is paid on the influence of joint dip angles on the anisotropic deformation behaviour , strength, mechanical properties, and failure modes of the CJRM. The experimental results show that the relationship between characteristic stress thresholds and joint dip angles is exhibited as a typical U-shape. Crack unstable growth ( σ cu ) and crack damage ( σ cd ) stress thresholds are more anisotropic than the crack stable growth stress threshold ( σ cs ), peak stress ( σ p ) and residual stress ( σ r ). The CJRM anisotropy mechanical parameters induced by stress gradually increases. Three main failure modes are observed throughout the loading process with respect to the joint dip angles. The results presented in this paper are significant for understanding the mechanical behavior of anisotropy in rock engineering.