Sliding instability mechanism and influence rule of fault zone used for mining operation of underground metal mine

Taking a mine in Shandong Province as the engineering background, the study is carried out by using three-dimensional discrete-continuous coupled numerical methods and theoretical analysis to address the slip instability of fault zones under mining action. The influence of rock mass RMR, original rock stress, mining conditions and fault origin on the stability of the fault and its surrounding rock in the near area is calculated, and a quantitative assessment method of the influence of mining unloading on the fault is established based on two indicators, namely, the amount of fault slip and the difference of shear stress. The results show that with the increase of mining span and mining depth, the disturbance area of the fault gradually increases; with the increase of RMR, fault dip, and the distance from the mining site to the fault, the disturbance area of the fault gradually decreases; when the dip of the fault is less than 45°, the fault is easy to slip; on this basis, the disturbance response criterion and the Mohr-Coulomb criterion are used to analyze and obtain the positive stress and shear stress difference on the fault under the influence of different conditions after mining. On the basis of this, using the perturbation response criterion and Mohr-Coulomb criterion, it analyzes and obtains the change rule of positive stress and additional shear stress on the fault under different conditions, which reveals the influence mechanism of the mining action on the fault slip instability. The correlation between the influencing factors is weak, and the correlation between the distance from the quarry to the fault and the amount of fault slip is the strongest; the Kernel Ridge Regression algorithm is used to establish a prediction model for the amount of fault slip, and the prediction error of the model is verified to be less than 10%, which indicates that the model can realize the prediction of the amount of fault slip under the action of mining, and the study provides theoretical ideas and predictions for the stability analysis and prediction of the fault slip and its near-area surrounding rock under the action of mining. This study provides theoretical and conceptual support for the analysis and prediction of fault slip and its near-area surrounding rock under mining action.