Study on the Mechanism of Repeated Mining Tremor in Multiple Key Layers: A Typical Case Study

Mine tremors in coal mines have evolved into an important factor affecting the safety of underground production and surface buildings. In order to address the problem of frequent mine tremors in Dongtan coal mine, a model of repetitive mine tremors in multi-layered key layers was established by using theoretical analysis and field observation. The process of mining tremor energy accumulation and release was analyzed, and the theoretical equation of mining tremor energy calculation was proposed, and the mechanism of occurrence of repetitive mine seismic was obtained. The results show that the concentrated release of gravitational potential energy and elastic strain energy due to the periodic fracture of multiple key layers is the fundamental cause for the frequent repetitive mine tremors in Dongtan coal mine. The energy of repeated mine tremors in multi-layer key stratum mainly comes from two parts, one is the release of gravitational potential energy caused by the key-layer fracture, and the other is the elastic strain energy released by the fracture of the key-layer and its controlling rock layer. The paper successfully predicted the maximum mine tremor magnitude of 3.15 Richter scale during the mining process of 6305 working face, which can correspond well with the maximum mine tremor magnitude of 3.04 Richter scale monitored by microseismic equipment. The research results can provide a reference for predicting the maximum magnitude of mine tremors under similar stratigraphic conditions.