Surrounding Rock Control Technology For Roadway Driving Along Goaf Of Isolated Coalface Using Top-coal Caving In Close Coal Seams

Taking 5213 working face and 8213 isolated island top-coal caving face(IITCF)coal seam group(CSG)in Yanjiahe Coal Mine as the research background.Theoretical analysis,numerical simulation and field measurement are used to systematically analyze distribution law of mining stress of IITCF in close distance CSG and surrounding rock control of roadway driving along goaf.Emphasis is laid on the analysis of the distribution law of lateral abutment pressure of 8213 IITCF under the condition of both side goaf and 5213 working face in three different layout modes above it.Supporting parameters and reasonable position of roadway driving along goaf in 8213 working face are optimized.And industrial tests have been carried out.The main achievements are as follows:(1)When mining in close distance CSG,the distribution law of lateral abutment pressure in top-coal caving face with underlying isolated island is determined by the layout mode of overlying working face.When the overlying working face is arranged in different ways,the distribution law of lateral abutment pressure(decreasing area,increasing area,peak stress)of the underlying island top-coal caving face is quite different.(2)When the inward location is arranged,the overlying goaf side fixed abutment pressure and the underlying island top-coal caving face side fixed abutment pressure overlap.As a result,the influence range of lateral abutment pressure of top-coal coal caving face with underlying isolated islands is large.Peak stress is large.The decompression area is small.It is not conducive to roadway driving along goaf.(3)When the outward location is arranged,the underlying island top-coal caving face is located below the overlying goaf.The peak stress of lateral abutment pressure of the underlying island top-coal caving face and increasing area is small,which is beneficial to roadway driving along goaf.But the overlying working face is located near the maximum bending subsidence caused by mining near the underlying island top-coal caving face,which is not conducive to driving and maintenance of the mining roadway at the overlying working face.Therefore,overlap location of overlying working face is more reasonable.(4)When overlap location is adopted,the peak value of lateral abutment pressure decreases greatly and the decompression area is small in the underlying island top-coal caving face.And the mining roadway of the overlying face is avoided to be located at the maximum sinking bend above the goaf on both sides of the underlying island top-coal caving face,which is beneficial to roadway driving along goaf.(5)The reasonable position of roadway driving along goaf in the underlying island top-coal caving face is determined,and the supporting parameters of bolt and anchor cable are optimized.The industrial test shows that the layout of overlying working face,the location of roadway driving along goaf and the surrounding rock control scheme of underlying island top-coal caving face are reasonable.