Strength Behaviour of Shale Rock Subjected to Polyaxial Stress State: A Numerical Approach

The design and construction of underground openings in shale type of rocks requires the understanding of coupled effect of anisotropy and polyaxial stress state. Therefore, in the present work, an attempt is made to develop a methodology for analyzing anisotropic rocks under a polyaxial stress state. The methodology developed in the present work depends on basic experiments (Uniaxial and Triaxial) and the Discrete Element Method (DEM) based numerical modeling. It is observed that the interaction properties between two layers of the anisotropic rock are significant for the numerical simulation of underground structures. The interaction behaviour of two layers is dependent on shear stiffness (Ks), normal stiffness (Kn), joint tensile strength, joint friction angle, and joint cohesion. Therefore, in first step the interaction properties are found by simulating experimental uniaxial and triaxial results. Finally, the obtained properties are used for the simulation of coupled effect of polyaxial stress state and anisotropy.