Analysis And Prevention Of Rock Burst On Working Face Under The Influence Of Fault

Rock burst is one of the major geological disasters in mining in China.When the coal mining face is arranged near the fault,it is often accompanied by the rock burst with great strength,and the law of rock burst near the fault is very complicated.Therefore,it is great significance to explore the law of rock burst in the working face affected by faults.In this paper,the actual situation of 7 coal seam 7335 working surface of Mine is taken as the engineering background,combined with theoretical research,numerical simulation calculation and practical analysis,discussed the impact risk of the work surface affected by the fault.Firstly,the influencing factors of face impact hazard are determined by theoretical analysis.Secondly,the stress evolution characteristics of surrounding rock under the influence of fault in 7335 working face are analyzed by means of numerical simulation.Combined with the actual microseismic activity of 7335 working face in the process of mining,the surrounding rock movement law of the two stages of advancing along the fault and passing through the fault is analyzed.At last,the prevention and control scheme is made.The content and conclusions include the following:(1)According to the analysis,fault is one of the main factors inducing impact of working face.Secondly,the overburden space structure of 7335 working face is short-arm "F" type fracture by analyzing the evolution law of working face roof.The causes of induced shock under dynamic and static loading were analyzed.It is considered that the overlying fault of several thick and hard rock strata and the seismic action caused by the gyratory movement occur in the high static load working face affected by the tectonic stress,thus the impact failure occurs beyond the limit equilibrium state of the surrounding rock.In addition,based on the basic top fault model,it is analyzed that the faults in front of the working face gradually enter the rebound zone when the adjacent fault production,and the normal stress of the fault is reduced,which is more likely to occur dislocation,thus increasing the impact risk of the working face.(2)Through FLAC3 D numerical simulation analysis,the working face in the advance stage along the fault,the two sides of the fault barrier effect is obvious.The stress of coal rock mass in the middle face is higher than that of coal rock mass on sides.The effect of stoping disturbance is amplified and the stress concentration degree is increased.The leading stress of the working face in the fault stage is obviously affected by the fault.It is obviouly that high stress is distributed along both sides of the fault.The stress concentration coefficient reaches the maximum at the intersection of the fault andthe two lanes,and the influence degree reaches the maximum when the fault passes through the middle of the working face.It show that the fault has great influence.(3)Microseismic monitoring and seismic wave CT inversion at the stoping stage of 7335 working face are analyzed.When the working face advances along the strike of the fault,the activity of overburden is intensified in the stage of overburden movement and the fault scope is wider.Energy accumulation and dispersion in overlying strata are frequent and accompanied by large energy events.When pass the fault section,the triangular area enclosed by the working face and the oblique fault has a frequent microseismic activity.From the perspective of the occurrence of microseismic horizon,the frequency of microseismic decreases in the stage of fault clamping,but the energy release degree increases.In the working face passes the fault stage,the microseismic events were close to the coal seam,and the high-energy rock strata broke in the high roof.The abnormal areas of high wave velocity are mainly concentrated on the middle of the working face and near the fault.The impact hazard of the chute roadway was significantly higher than that of the material roadway,and the monitoring results were generally consistent with the simulated stress distribution.Finally,the circulation and difference of microseismic activity under the influence of faults are explained with the stick-slip model.(4)According to the research,a monitoring and prevention program for rock bursts is formulated to reduce the risk level of rock burst in the monitored area.Ensure the safety of work surfaces and the safety of staff.The effect of pressure relief is analyzed in time.And it is concluded that the pressure relief measures based on roof deep hole blasting have good results.(5)This paper can effectively guide the safe mining of 7335 working face.It also provides theoretical support and technical guidance for other with similar conditions.The thesis has 61 figures,9 tables,99 references.