Application of CT inversion monitoring and early warning technology in microseismic anomaly area

In order to solve the problems that microseismic monitoring can only reflect the danger of the area where the microseisms are located, and CT inversion monitoring cannot reflect the current danger level of the working face in time, taking the 3105 working face of Dongshan Gucheng Coal Mine in Jining, Shandong as the engineering research background, a microseismic-stress multi-dimensional information monitoring and early warning method is proposed. The method combines short-term microseismic monitoring and medium and long term seismic wave CT inversion monitoring technology to identify the impact dangerous area of the working face. And the method combines the large-scale monitoring results based on medium and long term CT inversion, uses microseismic data around the working face to correct them so as to realize the real-time and dynamic monitoring and early warning of the medium and long term stress evolution of the working face and short-term microseismic accumulation. According to the abnormal situation of spatial and temporal distribution of microseismic events in August 2019 in 3105 working face for nearly one month, it is judged that the coal pillar area of the narrowing section in front of the working face is the abnormal stress area, and the CT inversion technology is adopted for dangerous area division and early warning. According to the results of CT inversion, the range of dangerous areas of strong and medium impact is given, and the high wave velocity impact dangerous area of 3105 working face is determined to be 100-200 m ahead of the material roadway and transportation roadway of the 3105 working face. According to the results of CT inversion, in accordance with the principle of zoning management, the corresponding pressure relief measures combining large diameter drilling of coal seam, coal blasting and deep hole blasting pressure relief are adopted for the high wave velocity impact dangerous area. The application results show that the seismic wave CT inversion technology can predict the corresponding relationship between high wave velocity and abnormal pressure area in two roadways accurately, predict the impact dangerous area effectively and can distinguish the danger level. After implementing pressure relief measures in dangerous areas with high wave velocity, the microseismic frequency and energy in the area are reduced effectively. The microseismic frequency and energy are reduced from 515, 12×10⁵ J to 338, 5.98×10⁵ J, are decreased 34.4% and 50.2% respectively. The pressure relief effect is obvious.