Research On Three-dimensional Stress Evolution Characteristics Of Mining Coal And Rock And Its Influence On Rock Burst

In recent years,with the increase of coal mining depth and the continuous increase of in-situ stress,higher energy accumulates in the coal and rock masses.Affected by the excavation disturbance,the internal energy of the coal and rock masses is rapidly released in a short period of time,resulting in dynamic disaster accidents such as rock bursts.,A serious threat to the life safety of the operators and the high production and efficiency of the mine.The sudden change in the stress state of coal and rock mass is one of the key factors inducing dynamic disasters.Therefore,monitoring the size of coal and rock stress is of great significance to the prevention and control of rock bursts.This paper adopts the methods of experimental research,field measurement and theoretical analysis.With the 7335 working face of Xuzhuang Coal Mine as the background,the ground stress and three-dimensional mining stress of the working face are measured,and the three-dimensional stress evolution characteristics of the mining coal and its impact on the impact ground are analyzed.The impact of pressure.The main research conclusions of the paper are:(1)In order to facilitate the on-site installation of the stress monitoring system,the stress sensor in the stress acquisition system is optimized to shorten its length by152 mm,and the front end of the stress sensor is curved.The optimized stress sensor is tested for performance.The test results show that the optimized stress-sensing shrapnel has good sensing performance and the independent working performance of the three-dimensional stress-sensing shrapnel.(2)The maximum principal stress of the 7335 working face is 13.56°,its value is 15.43 MPa,the intermediate principal stress is 73.61°,its value is 12.17 MPa,the minimum principal stress dip is-8.63°,its value is 10.27 MPa.The directions of the maximum principal stress and the minimum principal stress are both close to the horizontal direction,and the intermediate principal stress is close to the vertical direction.Therefore,the 7335 working face is dominated by tectonic stress.The azimuth angle of the maximum principal stress of the 7335 working face is 133.14°,which is approximately perpendicular to the Liuzi lane and the material lane of the7335 working face,which is not conducive to the support work of the two roadways.(3)The three-dimensional stress of coal mining experienced four stages: slow increase,sudden increase,stability and sudden drop.The range of mining stress in the vertical direction is the largest,the range of mining stress in the direction of the coal seam's inclination is the smallest,and the range of mining stress in the direction of coal seam strike is between the two.Although the stress value in the vertical direction is greater than that in the horizontal direction,the degree of stress concentration in the horizontal direction is the same or slightly higher than that in the vertical direction,indicating that the stress concentration in the horizontal direction is also an important factor in inducing rock bursts.When the measuring point is closer to the working surface,the stress values in the horizontal two directions will decrease earlier than the vertical.(4)The statistical analysis of the microseismic events near the mining stress monitoring point found that when a microseismic event occurs,the three-dimensional stress value of coal and rock will increase to varying degrees and then fall.When the three-dimensional stress increases suddenly,the stress increase in the horizontal direction is often higher than the stress increase in the vertical direction.According to the theory of dynamic and static load impact,7335 working face is affected by ground stress and mining stress,coal and rock accumulate high energy.When the shock wave acts on the coal and rock mass,the accumulated energy is suddenly released to induce dynamic disasters such as impact.Studies have shown that the sudden increase and sudden drop of horizontal stress of mining coal is also an important factor in inducing dynamic disasters such as shock;the sudden increase of three-dimensional stress can be used as a precursor to rock bursts.The test results have certain guiding significance for the prevention and control of rock bursts.This paper consists of 31 Figures,12 tables and 77 references.