Disturbed zone calculation and stability evaluation method of footwall slope with slip-shear failure under excavation

The slip-shear failure type of footwall slope is a type of beding slope that often appears in mining engineering, which has the characteristics of strong suddenness and extensive failure range. How to quickly and accurately define the plastic disturbed zone of excavation and evaluate its stability is vital for safety control. In this work, the failure mode and characteristics of this type of slope are first revealed by numerical simulation tests. Then, according to the failure mode of the slope, considering the uniaxial compressive strength of the rock mass, the mathematical equation describing the excavation disturbed zone is established. Finally, a new mechanical truncation method (MTM) is proposed to calculate the excavation disturbed zone and stability of the footwall slope. It is found that the MTM can accurately characterize the disturbed zone. The calculated limit cutting depth, disturbance thickness, and safety factor are in good agreement with the numerical simulation results, and the evaluation results are safer than numerical simulations. The maximum thickness of the disturbed zone determines the depth of the anchor end of the anchor cable. The disturbed zone indicates the critical area for reinforcement and provides engineering construction and monitoring guidance for the footwall slope.