Shear-slipe Deformation and Critical Stress State Discriminant Criteria for Fault Rock Masses

Abstract

Deep fault rock mass may undergo large-scale slip deformation under the action of tectonic stress or engineering disturbance, which has a non-negligible impact on engineering and human activities. In order to reveal the stress and motion characteristics of fault rock mass in the process of sliding friction, the shear slip characteristics and slip critical stress state of single-fracture granite in the process of normal stress isogradient decrease were investigated on a self-developed large displacement shear deformation device for fractured rock mass. Under the action of friction strengthening, the unstable slip deformation of fractured rock mass does not increase infinitely, the critical shear stress for shear slip of single-fracture granite is about 1.79 times the normal stress in this state, during the isogradient reduction of normal stress, the average reduction rate of the maximum shear stress is about 0.145 MPa/s, the average maximum slip rate is about 8.4 μm/s, and the average maximum slip acceleration is about 0.547 μm/s2. A theoretical model among various stress parameters under critical slip conditions was established with the help of the Mohr-Coulomb criterion, and the model was compared with the measured parameters, and proved to better match experimental results. This work provides a reference value in predicting and evaluating the instability and slip state of fractured rock mass.

Keywords

• faulted rock mass
• friction slip
• shear deformation
• mohr-coulomb criterion