Numerical simulation of the shear behaviors of rock joints under the direct shear test

This paper employs the Particle Flow Code in 2 dimensions (PFC^2D) to simulate the shear behaviors of rock joints under direct shear tests. A series of rock joints and regular joints with various saw-tooth angles are investigated. The shear resistance - shear displacement relationship, shear strength parametas, crack propagation, and failure modes are observed and investigated. Based on the numerical simulation results and application of the regular joint models, the simulation results compared well with the shear strength models of Patton [3] and Zhang [4] for higher and lower normal stresses but only compared well with the model of Zhang [4] for critical normal stresses. For observation of crack propagation, the initial micro-cracks appeared near the saw-tooth interfaces at 60% ∼ 70% of the peak stress state before the peak. Soon, micro-cracks began to propagate into a macro-crack until the stress state reached the peak. The simulated failure modes are compare well with Zhang [4]. This paper further established the chart of the distribution of failure modes based on the saw-tooth angle and the normal stress conditions.