Numerical investigation on the shear behavior of rock-like materials containing fissure-holes with FEM-CZM method

Abstract

Holes, including their shape and distribution, significantly affect the performance in rocks. In this paper, a numerical investigation, based on a FEM-CZM method, was developed to explore the shear behavior of rock-like materials containing fissure-holes. The laboratory uniaxial compression test was initially performed, and a corresponding numerical model was established by inserting zero-thickness cohesive elements into finite elements globally, the mechanical parameters were acquired by parameter trial and error tests. Subsequently, numerical direct shear tests were conducted under the constant normal stress level. Finally, the mechanical properties, shear deformation, and cracking behaviors were respectively discussed. The results show that for rock-like materials containing fissure-holes, the shearing process can be divided into four typical stages from the perspective of the cohesive elements. In addition, the mechanical characteristics (i.e., peak shear strength, residual shear strength, and crack initiation stress), shear deformation, and cracking behaviors (i.e., crack initiation, propagation, and coalescence), as well as the coalescence mechanism strongly depend on the shape, ligament angle, and the combination of fissure-holes. Furthermore, based on the damaged cohesive elements, the rock bridge coalescence modes between two fissure-holes were identified as “DT” (dominated by tensile damage), “T” (tensile damage), and “S + T” (shear and tensile damage), respectively.