Prediction Analysis And Support Technology Research Of Rock Burst In Thick Coal Seam

Rock burst is a kind of strong destructive power phenomenon in coal and rock mass,and it has suddenness and diversity.At present,the most extensive theory about the mechanism of rock burst is that the elastic energy in coal and rock is stored over loading.Finally,the coal and rock mass destabilize and release the elastic energy.On coal mining,thick coal seam compared with thin coal seam and layered mining,thick coal seam has the characteristics of large mining height and large disturbance,so the possibility of rock burst is also high and it is especially in thick coal seam mine with deep depth.According the relevant regulations of the coal mine,the mine which the depth is more than400 m needs to monitor the rock burst.The prediction of rock burst has not been well solved because of the randomness and inaccuracy.Xiao Ji Han mine as the engineering background,thick coal seam rockburst has gestating time when it emerge rock burst.Creep-induced rock burst is easy to occur in the working face and the roadway that has already been produced under high stress.By means of theoretical and numerical simulation to forecast the rock burst of xiao ji han mine.The support of the roadway which has producedlarge deformation and impact is optimized and improved.The main research results are as follows:(1)Through the comparison and analysis of thin coal seam and the thick coal seam,we could use calculation to induce the relation curve of the elastic energy,the radius of the roadway and the depth of the coal seam under the geological conditions of xiao ji han mine.(2)The Creep-inducetd rock burst has the characteristics of spontaneity and delay.The "pseudo free surface" will be formed after the roadway which surrounding rock is destroied creeply.Some of the elastic coal body is relieved from three-dimensional stress state,finally,the rock burst in the weak area of the roadway is broken down.The surrounding rock is divided into the rapid unstable creep zone,the slow unstable creep zone and the stable creep zone because of the difference of the creep rate and the approximate range of three kinds of creep zones is calculated in xiao ji han,it provide the theoretical basis for the support of roadway.(3)Because the change area of coal thickness may affect the of the coal mine in xiao ji han,so a simple mechanical model of spring body is established and calculated to draw the conclusion that thick coal seam to thin coal seam the stress will increase,the view is proved by numerical simulation.(4)Through three stages mining of working face by the mean of flac3 D in xiao ji han,the possible area of rock burst in front of working face and abnormal stress areas in both sides of roadway are analyzed.(5)The problem that there is a small anchorage range in the original support and the effective pressure arch can not be formed in the roadway,rock burst and abnormal stress is also existing in roadway so the bolt + anchor + steel combined support is proposed,the monitoring of the abnormal stress area of coal thickness is strengthened and measures for release pressure boreholer should be implemented.(6)A partial measure for prevention and control of rock burst in front of working face is put forward.