Interactions between multi-fault activation and overburden movement, and the induced rock burst mechanism

In regions with multi-faults, the interaction between fault activation and overburden movement significantly increases the risk of rock bursts. In this study, the full process of “fault activation–overburden movement–stress evolution” during mining in a fault assemblage zone was reproduced by combining microseismic (MS) monitoring with a physical similarity model. On this basis, the mutual feedback patterns between multi-fault activation and overburden movement were identified, and their effects on rock burst were systematically examined. The results indicate that the fault dip direction, working face mining direction, and the relative positions of the hanging wall and footwall collectively govern the response of the fault to mining activities. Two distinct interactive feedback models are identified within the multi-fault and overburden system: one dominated by overburden movement and the other by fault activation. The latter model, governed by fault activation, is associated with more extensive, integrated fracturing of the overburden and consequently a higher rock burst risk. Furthermore, the varying degree of dynamic-static load superposition induced by fault activation is the fundamental cause of the differences in rock burst mechanisms. A sharp increase in stress before failure of the key strata, together with a sudden displacement mutation after failure, can serve as potential precursor characteristics of rock bursts jointly induced by multi-faults.