The Time-Dependent Failure Mechanism of Rocks and Associated Application in Slope Engineering: An Explanation Based on Numerical Investigation

In this study, a numerical model for long-term deformation and progressive failure of rock slope is presented. The model accounts for both rock heterogeneity and the initiation, activation, nucleation, and coalescence of cracks in rock slope through a stochastic local stress field and local rock degradation by using an exponential softening law. The time-dependent behaviour of rocks is taken as a macroscopic consequence of damage evolution and strength degradation in microstructure. A series of demonstrative slope cases containing preexisting joints are constructed and investigated. The slope instability occurs at a particular point in time when the rock strength is reduced to a certain value. The temporal and spatial evolution of joint linkage structures is numerically obtained, which clearly shows how the local stress field and damage evolution within the joint network contribute to the fracture pattern and the long-term instability. Then, a practical slope case in jointed and layered rock formations in Yunyang city is studied. The prevailing failure phenomena of the slope, including gradual surface scaling, sliding collapses, and block falling, are numerically reproduced, with an emphasis placed on the slope failure process and development tendency. There is a good agreement on the failure mode and instability time between the numerical simulations and the field observations.