Stability Analysis And Control Technology Of Roadway Driving Along Goaf With Hard Immediate Roof In 15# Coal Mine Of Duan Wang Mine

Duanwang mine is the main mine of Shanxi Shouyang Duanwang coal industry group.Its annual output is 3.0Mt,and 15# coal seam's immediate roof is K2 limestone,with a thickness of 1.10 to 2.60 m,average 1.4m.The thickness of coal seam is 3.19~5.02 m,average 4.05 m,and the bottom plate is a sandy mudstone with a thickness of 5m.In order to further reduce the loss of coal pillar and optimize the support effectiveness,this paper takes the 15# coal as the project background to study the roadways driving along next goaf,the main achievements are as follows:The deformation characteristics of roadways driving along next goaf with hard immediate roof are described.According to the failure depth,self stability and the thickness of the immediate roof,this paper divides the support categories,and describes the supporting methods of each support category,expounds the key problems affecting the anchorage support in the field,and calculates and determines the support parameters theoretically.Through the 150505 return air roadway support In situ test,it is determined that the roof bolt torque should reach 300N·m,the anchorage length should be above 0.9m,the coal bolt torque should be between 200~250 N·m,and the anchorage length should be above 0.7m;the optimum length of the anchor cable is 4.3m,which provides the basis for the support work of 150505 workface and 15# coal seamroadways.Based on the analysis of the fracture location of the basic roof,it is concluded that when the coal pillar is greater than 7.6m,the roof stability of the retained roadway is more favorable.It is calculated that when the thickness of the direct roof is more than 3.9m,the roof weakening treatment is needed.This paper analyzes the reasons for failure of coal pillar test in duer Wang mine,and confirms that the best time for 15# roadway driving in Duwang mine is 133.7~167.1d.Through the combination of theoretical calculation and field conditions,the reasonable range of coal pillar size is determined to be 10~20m.Through numerical simulation analysis,it is found that the peak value of coal stress is at 6.5m away from the coal wall.In this paper,five kinds of coal pillars with different width of 10 m,12M,14 m,16m and 18 m have been simulated.The stress distribution of coal pillar below 12 m is sharp without smooth bearing section,and the roadway deformation is large.The stable elastic core exists in 14 m,16m and 18 m pillar,which is beneficial to its long-term stability,considering the safety and benefit of production,Simulation verifies that 14 m coal pillar meets the requirement of recoveryUnder the design of coal pillar size and support scheme,observing 150505 Transportation roadway deformation for 30 days,The total deformation of the roof and floor is about 100 mm,the total deformation of the two sidewall is about 155 mm,the total deformation is small,and the surrounding rock deformation control effect is good.