Study On Rockburst Prevention And Control Technology Of External Staggered Coalface In Lower Layer Of Near Fault Area

When the multi-coal working face is mined,the upper and lower working faces are mostly in a dislocation layout(internal and external).When the lower coal is recovered to the vicinity of the large fault,it is easy to form a faulty working face.The 9119 working face of the 9-coal seam of Zhangshuanglou Coal Mine is located at the 7119-coal face of the 7 coal seam and directly below the F9 large fault protection coal pillar.It is close to the F9 large fault.When the 9119 working face is recovered,it is not only affected by the upper 7 coal fault coal pillar.The high static load is also affected by the strong dynamic load of the F9 large fault and the multi-layer coal overburden,forming a faulty working face under the coal seam in the fault zone,and the impact risk is high.Based on this,this paper takes the 9119 working face of Zhangshuanglou Coal Mine(the outer coal seam working face in the fault zone)as the research object.Firstly,the stress field and structural stability characteristics of the faulty working face under the coal seam in the fault zone are analyzed.Then,based on the geological profile of 9119 working face,the numerical simulation is carried out,and the reasonable arrangement position of the side roadway along the fault is designed.Combined with the micro-seismic monitoring data,the micro-seismic activity law of the faulty working face under the coal seam in the fault zone is analyzed.Finally,the fault zone is proposed.The prevention and control measures for the impact rock pressure on the wrong working face of the lower coal seam are applied on site.The following conclusions are drawn This paper analyses the stress field and structural stability characteristics of the external staggered coalface along faults,designs the rational layout of the roadway facing faults,studies the micro-seismic activity law,and puts forward the prevention and control measures for the rock burst and its field application at the external staggered coalface along faults.The results are as follows:(1)Theoretical analysis of the stress field and structural stability characteristics of the fault surface outside the fault.The stress field of the 9119 working face in the fault zone is mainly composed of the self-heavy stress field,the supporting stress field and the tectonic stress field.The overburden structure is a short arm "T" structure and a short arm "F" structure.The main sources are: dynamic load of 7 coal overburden movement,dynamic load of fault slip,dynamic load of 9 coal overburden movement,static load of 7 coal fault coal pillar and static load of 9 coal fault coal pillar.After the load is superimposed,the dangerous position of the impact is mainly concentrated near the square,fault,fold,and stop line.(2)The layout position of the 9119 working face roadway outside the coal seam under the fault zone was optimized.The numerical simulation results of FLAC3 D show that the stress below the 7-coal coal pillars with a fault of 40~100m is high and the static load is large.The closer the return airway is to the fault,the more obvious the stress changes before and after the roadway excavation;The selection has little influence on the stress of the fault coal pillar during the excavation,and has a certain influence on the stress of the roadway during the mining,and the overall stress increases by 20%~30%.From the angle of fault slip,the greater the distance between the return airway and the fault,the smaller the slippage of the fault.Considering factors such as fault slip,fault coal pillar area and return airway stress distribution,it is recommended to arrange the roadway below the coal pillar far from the fault,and the distance between the fault and the fault is kept between 50~70m.(3)Based on the micro-seismic data during the excavation of the 9119 working face of the coal seam outside the fault zone,the micro-seismic activity law of the 9119 working face was obtained.During the excavation of the 9119 working face in the fault zone,the mines are mainly concentrated in the first half of the roadway and the middle of the two faults.The number of mines in the second half of the roadway is small.The mines are mainly concentrated in the return air level.The number of mines and mines is obviously larger than that of transport roadways,and it is mainly located in the range of 0~300m and 510~704m.The former part is the influence of coal pillars,and the latter part is mainly the comprehensive influence zone of coal pillars and faults.(4)Combined with the impact characteristics of the faulty working face under the coal seam under the fault zone,the impact mine pressure prevention and control technology for the 9119 working face was obtained.The use of tunnel full-face pressure relief,coal pillar edge zone impact prevention and control technology,mining hard roof cutting technology and the use of reasonable mining speed and other technologies can effectively reduce the probability of large energy mines in actual engineering.The research results of this paper can effectively guide the safe and efficient production of NO.9119 working face.At the same time,it also provides theoretical and technical guidance for the relevant rock burst prevention design of the external staggered layout coalface along fault.