Study on microseismic characteristics of geologic anomaly region in coal and gas outburst seam induced by roadway excavation

Coal and gas outburst is one of the most serious threatens to the safety of mine operations，it is easy to cause and happened frequently in the fault and other geologic anomaly region.In this paper,we analyze the mechanism of microseism in fault activation induced by roadway excavation using an outburst mine in Guizhou province as an example.A high precision microseismic monitoring system was applied to monitor and measure the seismic time and space distributions.The evolution law of mining geological anomaly area during excavation was also studied.The results show that the locations of microseismic events are generally around the roadway during mining of working face,in the area of 112.8 m in front and 91.0 m in rear of the roadway.Mining-induced fault activation is the main cause of fault microseismic activities.Through real-time monitoring of the faults within influence range during mining,it is found that microseismic events increase in the area 15 m far from the fault area and the initial phase is dominated by high-energy vibration signals.When distance from the fault area decreases (5 m),microseismic events gradually increases to the peak and mainly distribute around the fault surface.As a new stable structure formed,the microseismic activities decrease gradually until reaching a stable state.It is also found that microseismic responses ex-ist in geological abnormal area under the influence of mining,which provides a new idea for the in-depth analysis of mechanism of fault controlled coal and gas outburst accident and the realization of accurate prediction of coal and gas outburst.