## 3 Analysis of Abutment Pressure Evolution Law Based on Microseismic Monitoring
### Analysis of the Microseismic Activity in the Tectonic Region  
In order to study the activity signs in the tectonic area during the mining process of the 1300 working face, the microseismic activity in the fault areas of FY15, Yf2, and Yf1 was statistically analyzed. As shown in Figure 6, the FY15 fault obliques through working faces 1300 and 1301. During the mining process, the 1300 working face successively passed FY15 and Yf1, and was affected by the Yf2 fault. In the early stage of mining, the stope was ahead of the principle of abutment pressure in the fault area, but it still induced the occurrence of a large number of small energy vibration events in the fault area, such as the plane projection of microseismic events from January 2014 to October 2014. With the advancement of the working face (1 January 2014-1 December 2014), the FY15 fault was within the influence range of advanced abatement pressure. Mining induced a few large energy events and a large number of small energy events. The spatial distribution of events was consistent with the fault morphology, indicating that mining induced fault activation. When approaching the FY15 fault (December 2014-31 December 2014), a large number of microseismic events were distributed in the rock mass around the working face, with large energy and small energy microseismic events alternately occurring with irregular frequency. Meanwhile, the advanced abutment pressure induced the Yf2 and Yf1 faults 300 m in front. It is speculated that this phenomenon is influenced by two factors: one is the gradual activation and induction of the major FY15 fault, and the other is the high mining rate of 6.4 m/s.  
Figure 5: Analysis of mining influence on the fully mechanized caving face (profile projection). (**a**) Projection along the dip profile. (**b**) Profile projection along the strike.  
Due to the violent activity of the fault, the 1300 working face implemented the corresponding safety measures in the mining process, reduced the mining speed of the working face to 4.8 m/s, and stopped production for consolidation in the later stage. At this time, although there were still a large number of microseismic events in the working face, the event energy was small, indicating that the high-stress area around the fault was transferred or weakened under the action of artificial \"weak thrust\" measures. The high-stress concentration was no longer obvious, and the sudden release of the weakened residual potential energy of coal rock mass was not enough to induce large energy events, which also indicates that the rockburst prevention measures effectively inhibited the occurrence of rockburst, such as during the period 1 January 2015-31 January 2015. After passing through the fault, on the one hand, the working face slowed down the speed of thrust mining, waiting for the full evolution of the overlying strata. Meanwhile, the fault was still in the range of the stop pressure relief zone. Therefore, the microseismic events significantly decreased, and some large energy events were suspected to be a rebalancing of the fault  
Figure 6: Microseismic distribution diagram of the 1300 working face and the adjacent 1301 working face.  
region, such as during the period January 2015-28 February 2015. During the period from January 2015 to 28 February 2015, microseismic activity became active again. On the one hand, the Yf2 and Yf1 faults entered the influence range of advanced abutment pressure; on the other hand, the FY15 fault was under the influence of hysteresis and the severe area.