Fault slip amplification mechanisms in deep mining due to heterogeneous geological layers

Rock bursts are complex phenomena directly linked to the mechanical interaction between mining operations and geological formations. Effective prediction and management of these events are critical for maintaining safety in deep mining. This study employs a 3-D heterogeneous model and the Finite Element Method (FEM) to assess hazards associated with fault slip near mining areas. Our investigation focuses on the amplification mechanisms of fault slip induced by heterogeneous geological layers. Numerical simulations demonstrate that heterogeneous strata amplify fault slip significantly compared to homogeneous models. This finding underscores the critical role of geological variability in fault behavior. We identify that longwall coal mining reduces local normal stress and increases shear stress, driving fault slip, contrasting with the pore pressure-driven mechanism in oil and gas extraction. Stress drop distributions from coseismic slip are calculated and validated using DC3D (a displacement and stress calculation tool for surface deformation in a semi-infinite medium), confirming the accuracy of our numerical approach. The simulations further reveal that stress and energy concentrations near fault slip zones, particularly adjacent to the mining horizon, elevate the risk of rock bursts. The findings align with field data from the "8.11 '' coal burst event at the Yuejin coal mine. The amplified fault slip and concentrated energy zones identified in the simulations correlate with the observed damage patterns in the "8.11 '' event. These insights underscore the necessity of incorporating geological heterogeneity in fault modeling to better predict and manage mining-induced seismic risks.