Distribution Of Regional Stress Field In Coal Mine And Its Influence On Rockburst

In the coal-forming areas of China,the geological and tectonic movements are complex,fault structures are developed,coal seams are buried at great depth,and regional stress field in the coal mine changes significantly,mining in working face may cause stress shifts and local stress concentration in the entire stope area,thus possibly inducing rock burst disaster.However,there is less research on the impact due to the regional stress change in the whole stope caused by mining to the occurrence of rock burst,as well as relationship between the evolution of the regional stress field in the mining area and the analysis of rock burst.This paper uses theoretical analysis,field measurement,vibration wave CT inversion analysis,numerical simulation and project practice to research the features of regional stress field distribution in No.3 mining area of Xingcun Coal Mine,and its influence on rock burst.And it establishes the monitoring and alerting system and stress transfer system in the stress concentration district.The regional stress field in the No.3 mining area of Xingcun Coal Mine is dominated by tectonic stress.Vibration wave CT inversion is used to detect and analyze the distribution characteristics of regional stress in No.3 mining area and its working faces.The following conclusions are drawn:(1)The distribution location of high stress concentration zone in No.3 mining area is constantly changing from the planes.However,in fault structure area,fold axis area and gathering main roadway of the rise area,the high stress state is always maintained,according to which the plane distribution map of stress in the geological anomaly area of No.3 mining area is drawn.(2)When excavating the working face,it is determined that the stress is concentrated in the area of about 300 meters before and after the heading face.Among them,the high stress concentration zone is at the heading face and ranges between 200 meters of its rear and 100 meters in front of it.The stress concentration degree behind the heading face is more obvious than that in front of it.(3)When stoping the working face,the high stress zone mainly concentrates between 0 and 420 meters of the advancing working face,and are affected more in the late mining stage compared than the initial mining stage.The paper analyzes the rock burst and large mining tremor events in No.3 mining area,and obtains the main controlling factors and failure characteristics of rock burst,meanwhile,establishes the internal relationship between the occurrence of rock burst and large mining tremor events and the regional stress field: In the local high stress environment,the effect of mining disturbance makes stress in these area more concentrated which induces rock burst or large mining tremor events.Through numerical simulation of the working face near the fault,it is found that when working face is 20 meters away from the fault near the roof,both the energy concentration degree and the stress value peak reach the maximum value.The energy accumulated in the roof will be released suddenly which results in large mining tremor events and induces rock burst.The above research results are used in the monitoring and early warning of stress concentration zone as well as establishment of the stress transfer technology scheme system of 3306-working-face of Xingcun Coal Mine.The CT detection technology of stress distribution and rock burst monitoring and early warning technology of the working face and No.3 mining area are carried out,the stress concentration area is determined,and local stress transfer measures,such as large diameter borehole pressure relief,coal body and roof blasting,are carried out in 3306 working face to relieve the rock burst risk,and the application effect is remarkable.There are 73 figures,27 tables,and 95 references in this paper.