Mechanical behavior of transversely isotropic rocks under uniaxial compression governed by micro-structure and micro-parameters

A numerical approach based on the particle discrete element method, in which the rock matrix is represented as flat joint contacts and weak planes are conceptualized as a set of parallel continuous smooth joint contacts, was adopted to simulate the transversely isotropic rocks. Firstly, this approach was validated through the comparison in the strength and fracture patterns of typical anisotropic rocks between simulation and experimental test results. Then, the influence of micro-structure of rock matrix and micro-parameters of weak planes on the mechanical behaviors of transversely isotropic rocks under uniaxial compression was studied. The results show that (1) good agreement is obtained between the numerical and experimental results in terms of strength and fracture patterns for typical U type or shoulder type rocks; (2) the types for the variation of uniaxial compression strength as a function of the weak plane-loading angles and the fracture patterns are slightly influenced by the tensile strength of weak planes but greatly influenced by the pre-existing micro-cracks in rock matrix, the stiffness and shear strength of weak planes; (3) shear and tensile micro-cracks in rock matrix are prone to occur in congregated region of pre-existing micro-cracks for the poor integrity in these regions. While the pre-existing micro-cracks in rock matrix has little influence on the occurring position of shear and tensile cracks on weak planes.