Rockburst Risk Evaluation And Application In Jinzhuang Coal Mine By Shock Wave CT Technique

In this paper,aiming at the realization of the safe mining of 3110-3 working face in Jin Zhuang coal mine,we studied the stress distribution of the working face before and after mining by means of comprehensive index method,numerical simulation and vibration wave CT method.The safe mining is realized.Evaluated the rockburst risk of 3110-3 working face by using comprehensive index method,and considered that the working face is not recoverable.However,considering the comprehensive index method is a macro evaluation based on the theoretical model and its accuracy needs to be further studied Therefore,we use numerical simulation and shock wave CT method to further study the impact risk of the surface.The experimental results show that there is a power function relationship between the stress and the longitudinal wave velocity,which indicates that the inversion of the shock wave velocity is an effective method to study the stress distribution in the region and to realize the early warning of the research area.The stress distribution was inversed by using the active CT industrial test on the 3110-3 working face,and it was found that there was one strong rockburst risk area,which was in the range of the open cut and the front 120 m Two medium rockburst risk areas,located in the working face close to the opening hole about 15 m of the material Lane and a mining area dedicated air return lane and 3110-3 outside the intersection of the traffic lane of the start of the 20 ~ 85 m range.Evaluation can be used as a guidance for rockburst control before coal mining.In order to monitor stress changes during mining,CT technique was adopted to depict velocity distribution in five periods.The results show that in the reliable regions,the stress concentration was observed in the left coal pillar near No.3110-2 working face in the first three periods,while mining process failed to activate F3 fault and stress concentration was not found in material roadway.In the last two periods,key rockburst areas were determined in the material roadway before working face,the end of traffic roadway and outside traffic roadway of No.3310-3 working face.The numerical simulation result also determined high stress regions in the coal pillar,but it indicated that stress concentration was more obvious around No.3310-3 material roadway influenced by fault,in other words,rockburst risk was more high in this area.In order to monitor stress changes during mining,CT technique was adopted to depict velocity distribution in five periods.The results show that in the reliable regions,the stress concentration was observed in the left coal pillar near No.3110-2 working face in the first three periods,while mining process failed to activate F3 fault and stress concentration was not found in material roadway.In the last two periods,key rockburst areas were determined in the material roadway before working face,the end of traffic roadway and outside traffic roadway of No.3310-3 working face.The numerical simulation result also determined high stress regions in the coal pillar,but it indicated that stress concentration was more obvious around No.3310-3 material roadway influenced by fault,in other words,rockburst risk was more high in this area.