A study of the mechanism of tensional slip instability and the energy release characteristics of normal faults under the influence of mining

Abstract

In recent years, the occurrence of dynamic failures induced by fault activation has increased in mining fields. To gain a better understanding of fault activation and energy release along faulted mining faces, a case study was conducted on a specific working face. This study utilized theoretical analysis, numerical simulation, and field measurements to investigate the influence of various factors on fault activation under mining conditions along faults, such as the width of the coal pillar between the fault and roadway (CPBFR), fault dip angle, overlying strata movement angle, and position of the working face with respect to the fault. The results of the study indicate the following. (1) An analysis of the simulation results reveals that fault shear slip does not result in energy release, whereas tensile slip can cause high-energy events. Formulas were proposed to determine whether tensile damage occurs during excavation of a working face on a normal fault, formulas were proposed to determine energy release after tensile damage on a fault, along with a qualitative expression characterizing the phenomenon. (2) When the working face is located below the normal fault, the length of the intersection between the fault line and the overlying strata movement line increases with increasing mining height, and the width of the CPBFR, the fault dip angle, and the overlying strata movement angle decrease. On the other hand, when the working face is located above the normal fault and the fault dip angle is greater than the overlying strata movement angle, the length of the intersection between the fault line and the overlying strata movement line increases with increasing mining height and fault dip angle and with decreasing CPBFR width and overlying strata movement angle.