Study on the influence of the fault dip angle on the stress evolution and slip risk of normal faults in mining

To address the frequent occurrence of activation-induced rock bursts in fault zones during mining, the stress evolution and fault slip behavior of normal faults with different dip angles during mining are studied by mechanical models, numerical simulations, and engineering practice. The establishment of a mechanical model of faults and the deduction of the relationships between the fault slip and the fault dip angle theta and fault friction phi reveal the necessary conditions for fault slip. The results of an analysis of a numerical model show that the change in stress state in the surrounding rock caused by mining is the root cause of fault slip. During the mining process, the risk of fault slip changes as the working face advances, and the risk of induced fault slip is higher during mining in the footwall. With the increase in the fault dip angle, the risk of fault slip first increases and then decreases, and the most dangerous dip angle in terms of fault slip is determined. The simulation and field results are consistent with the theoretical results.