Study On The Mechanism And Prevention Technology Of Large-area Pressure-Induced Rock Burst In The Working Face Of Menkeqing Coal Mine

The rockburst induced by large-area weighting of the hard roof in working face of menkeqing coal mine is an important disaster threatening the safety production of the mine.This paper using theoretical analysis,numerical simulation and support working resistance monitoring and microseismic monitoring comprehensive measures,such as the face of hard roof breakage characteristics,mining dynamic stress distribution of pressure and face hard roof area to induce impact ground pressure are studied,the key technical parameters of rockburst prevention and control in the working face are optimized,and 11-3102 working face rockburst prevention and control is formulated The measures are verified.The main results are as follows.(1)The law of overburden activity and incoming pressure in 11-3102 face is studied.The average periodic weighting step distance of 11-3102 working face is21.5m.The static load of 11-3102 working face is large in the process of mining.The vertical stress peak value and stress concentration coefficient of coal pillar are93.78 mpa and 5.12 respectively in the case of "first square",and 110.80 mpa and6.15 respectively in the case of "second square".The whole coal pillar is in a high stress state.The stress peak is about 5-10 m in front of the work,and the stress concentration coefficient is as high as 5.60.(2)The distribution of key strata of overburden and "key strata of induced thrust" are studied.Based on the mechanical analysis and field measurement of "two zones" of overburden,it is concluded that the sub key layer I is 17.68 m medium grained sandstone,the sub key layer II is 18.95 m medium grained sandstone,the sub key layer III is 25.00 m siltstone,the sub key layer IV is 45.70 m fine-grained sandstone,fine grained sandstone with thickness of 316.90 m is the main key layer.It is judged that the second subcritical layer is "induced thrust critical layer",and the second is subcritical layer 1.The uniaxial compressive strength of 3-1 coal is 53.56 MPa,and the critical load needed for impact is small.(3)The key factors causing the disaster of strong mine pressure in the return air roadway of 11-3102 working face are analyzed.The static load of the working face mainly comes from the advance bearing pressure of the working face and the lateral bearing pressure of the coal pillar.The dynamic load mainly comes from the energyreleased when the thick hard rock strata such as the sub key layer and the main key layer break.The dynamic load is transferred and overlapped with the high static load stress at the side of the coal pillar,resulting in the impact.The field shows that the impact of the working face is mainly concentrated on the side of the return air chute.The rock burst type of 11-3102 working face is typical "roof" + "coal pillar" type.(4)The scheme of top cutting and side pressure relief of air return roadway in11-3102 working face is established and implemented on site.According to the results of theoretical analysis,numerical simulation and field test data analysis,the pressure relief parameters are optimized,and the pressure relief scheme suitable for the field is obtained.After the roof deep hole blasting and the large-diameter borehole pressure relief of 3102 return air roadway and coal pillar stress concentration area,the frequency and degree of rock burst are reduced.