Rock burst prevention technology based on seismic CT detection in wide section coal pillar

To overcome the problems of easy occurrence,frequent occurrence and difficult prevention of coal pillar rock burst in deep mine,taking the rock burst in 1301 roadway with 80 m wide coal pillar as an example,based on numeri- cal simulation and microseism data analysis,the mechanism of rock burst in wide coal pillar was studied. The seismic CT in-situ detection technology was used to evaluate the risk of rock burst,and the corresponding prevention and con- trol scheme was put forward. The results show that the weak burst tendency of No. 3 coal seam and the strong burst tendency of roof rock stratum were the intrinsic condition of rock burst,the high gravity stress and strong tectonic stress were basic static loads,and the lateral abutment pressure of goaf was incremental static loads. When the vertical stress exceeded the critical abutment pressure,it provided the force source condition for the occurrence of static load type rock burst in wide coal pillar. By inversing the wave velocity from the actual seismic wave rays,the seismic CT in-situ detection technology can reflect the distribution and structural characteristics of the static load,and establish a risk as- sessment model of rock burst with the abnormal coefficient of wave velocity CA and the gradient coefficient of wave ve- locity CG as the main factors. In terms of the actual mining conditions in the impact area of wide coal pillar,a near- complete observation system was designed and arranged. The seismic CT detection showed that after the occurrence, the burst hazard indices were C = 0. 5-0. 7 and had moderate degree burst hazard,the burst hazard index of the side of transport channel was higher than that of goaf,which indicated that the stress of coal pillar had transferred from the side of goaf to the side of transport channel. The local fractured zone had high risk of roof caving or rib spalling acci- dent. The multi-level prevention and control technologies based on static load transformation were formulated including a large-diameter borehole pre-relief technology was used to transfer concentrated stress and dissipate elastic strain en- ergy of roadway side;the 2. 4 m / d advancing speed of working face was determined to reduce mining disturbance;and the support reinforcement of full roadway section was designed to improve the anti-impact ability. Through the above measures,the monitoring stress did not occur sudden increase,and the microseism energy and frequency was gentle. In 1301 working face,the wide coal pillar area had safely been recovered,and the control effect was obvious.