Study On The Size Of Yield Pillar And Technique Of Surrounding Rock Control In Guocun Coal Mine

With the gradual depletion of superior coal mining and the reduction of coal resources,three-soft coal seam mining is emerging at a fast pace.However,the problems of large deformation,high support cost and large pillar size of the gateway are the technical problems restricting the exploitation of the three-soft coal seam.The size of pillar and the support condition of gateway are discussed in this paper,field investigation,theoretical analysis,similar simulation and field industrial test are adopted,and the relationship between the size of the yielding pillar and the surrounding rock control of the gateway is systematically studied.The main conclusions are as follows:The surrounding rock of the gateway in the three-soft coal seam is characterized by the roof overall subsidence,the sides' horizontal movement and the serious floor deformation and failure,surrounding rock instability mode of inclined roof soft-coal gateway is divided into two: two-side extrusion rheological instability and roof compression dislocation instability.The bearing characteristics of the yielding pillar show that following the plastic failure on both sides,the bearing capacity decreases gradually till the the pillar is fully yielded when the bearing capacity is stable but less than that under original elastic condition.According to soften and stiffen characteristic of different size pillar,thepillar partition critical value of pillar yield bearing is proposed.According to the different plastic range of pillar,the pillar size is divided into disconnection,connection,overlap,complete overlap of stress close to goaf and gateway.The calculation formulas of stage pillar and narrow pillar are determined.The size of yielding pillar is calculated in Guocun mine,the actual size of the pillar is determined,and the cooperating control technique of active support of anchor bolt(anchor cable)and passive support of multi-direction contractible abnormal shed is proposed on the basis of coal-pillar yield load,which is carried out,field industrial test by the and the effect is remarkable.