Study On Overburden Movement And Its Influence On Stope Rock Burst Risk In Fully Mechanized Top Coal Caving Mining Of Yadian Coal Mine

Binchang mining area in Shaanxi Province is a typical mine area prone to rock burst in China.The occurrence of rock burst disasters generally has the main characteristics of late occurrence,short outbreak time,serious disasters and concentrated disaster mines.Yadian Coal Mine is located in Binchang mining area.Its ZF1417 working face is a fully mechanized top coal caving face with a thickness of8m.There is a 387m thick medium grained sandstone at 85.7m above the No.4 coal seam.The mining overburden movement is relatively violent,which is easy to cause strong ground pressure behavior of the working face.Considering the weak impact tendency of coal seam and roof,it is necessary to study the rock burst risk of ZF1417fully mechanized top coal caving mining.For this reason,this paper uses theoretical analysis,physical simulation,numerical simulation and field measurement to study the movement law of overlying strata,ground pressure behavior law and the risk of rock burst in stope.The fracture characteristics of 387m thick medium grained sandstone are studied by theoretical analysis.As the first working face of ZF1417 fully mechanized top coal caving face,the hard thick medium grained sandstone is in the"plate"mechanical state of four sides fixed support,and the ultimate collapse distance is 318m,which is much longer than the working face length of 230m,so the hard thick medium grained sandstone will not break.This result is verified by physical simulation experiment.Theoretical analysis,numerical simulation and field measurement are used to study the distribution characteristics of advance abutment pressure in working face.The theoretical analysis shows that the peak value of advance abutment pressure is17.8m in front of the working face;the numerical simulation shows that the maximum influence range of advance abutment pressure is more than 200m,the peak value is about 29.4Mpa,the stress concentration factor is 2.14,and the peak value is about15m in front of the working face;the field measurement shows that the influence range of advance abutment pressure is greater than 200m,indicating that the peak area of advance abutment pressure is located in the working face It is about 20m in front of us,which is basically consistent with the theoretical and simulation results.The influence range of advance abutment pressure in transportation and return air roadway is about 120m in front of the working face,and the obvious influence range is about70m in front of the working face,and the peak influence is 30-35m in front of the working face.It is found that the roof separation phenomenon occurs above the bolt support and under the anchor cable support.It is necessary to strengthen the support management of the anchor cable and increase the pre tightening force to give full play to the supporting role of the anchor cable.The monitoring results of microseismic activity show that the energy of microseismic activity is mostly less than 10~3 J during the advancing period of working face;however,during the period of"square",the energy of microseismic activity is significantly enhanced;at the same time,the total energy of daily microseismic activity,the maximum energy value of daily microseismic activity and the frequency of daily microseismic activity are positively correlated with the advancing speed of working face.The working face advancing at a speed of 5m/d can significantly reduce the intensity of the microseismic activity.As ZF1417 fully mechanized caving face is the first mining face in the mining area,and the overlying 387m thick medium grained sandstone is in the complete supporting bearing state,and the overlying load can be transferred to the surrounding coal and rock mass smoothly,so the occurrence of rock burst is not detected in the working face,and the impact risk of ZF1417 fully mechanized caving face is small.There are 93 pictures,18 tables and 74 references.