# Numerical and Field Investigations of Tremors Induced by Thick-Hard Strata Fracture
###### Abstract  
Large energy mining-induced tremors are generally caused by the rupture of thick-hard overlying strata, and the roadway is prone to rockburst danger under its dynamic load. Through numerical simulations, the laws and influencing factors of stress, deformation, fracture and energy caused by mining-induced tremors (red bed breaking) were revealed, and the results were verified by field observations. The main conclusions were obtained: (1) the tensile stress and the compressive stress were concentrated in the middle of the thick-hard rock and both sides of the goat, which were prone to tensile and shear failure type caused by mining-induced tremors, respectively; (2) after the goat was formed, the compressive stress around the roadway was transformed into tensile stress. When a strong mining-induced tremor occurred, the tensile stress increased further. Meanwhile, when it was close to the tensile strength of the coal around the roadway, a rockburst occurred; (3) the energy of the mining-induced tremor released by shear failure was larger than that of the tensile failure. With the increase in shear strength of the roof, the released energy also increased; (4) according to the frequency-spectrum of the mining-induced tremors located in the extremely thick-hard overlying strata above the working face in the Baodian coal mine, the dynamic load generated by the tremors was superimposed on the high static load around the roadway, which was very likely to induce the instability of the roadway. The research conclusions have certain guiding significance for rockburst prevention in coal mines with thick-hard strata roofs. thick-hard overlying strata; rockburst; mining-induced tremors; microseismic monitoring; dynamic load 20221211151 20221211151 20222121151 20222 27 October 202  
Scholars have conducted many studies on the occurrence mechanism of mining-induced tremors. For example, [PERSON] et al. used satellite interferometry to study the surface subsidence caused by mining-induced tremors [9]. [PERSON] et al. suggested a method to fit the mining volume of the coal body and the energy released by mining-induced tremors [10]. [PERSON] et al. monitored the MS events in the mining process through using a self-built, high-precision MS monitoring system, and analyzed the change characteristics of the MS parameters before the occurrence of two rockburst accidents [11]. [PERSON] et al. studied the ground tremors induced by different failure forms, and found that the ground tremor was mainly determined by the focal mechanism, distance, and azimuth [12]. [PERSON] et al. studied the static stress transfer in the surrounding rock caused by two high energy events, based on the focal mechanism [13]. [PERSON] et al. studied the relationship between the b value and MS events, and found that the b value tended to decrease before the high energy event, and increase significantly during the event [14]. [PERSON] et al. proposed a calculation method of rock damage, stress, and strain, defined by a focal moment tensor (MT), and studied its trend in work face mining [15]. In addition to field investigation, many researchers have also conducted fruitful studies in the numerical simulation of mining-induced tremors. For example, [PERSON] et al. used the boundary element method to simulate the instability of a fault caused by the mining, indicating that the mining led to the increase of deviatoric stress around the fault and promoted the fault instability [16]. A simplified numerical model was developed to calculate the potential seismic response of the faults to the undercut advance [17]. [PERSON] et al. extended the implicit to explicit sequential solution method (IESSM) in Ansys/Ls-dyna to explore the failure behavior of an underground chamber caused by static in-situ stress and mining-induced tremor disturbance [18]. [PERSON] et al. studied the influence of the dynamic load generated by different angles of roof fracture on gob side entry retention [19]. [PERSON] et al.