Study On The Stability Control Technology Of Surrounding Rock For Gob-side Entry Driving Foward The Mining Face Separate By A Narrow Goaf

The surrounding rock stability control of the gob-side entry driving foward the mining face is still a major technical problem in coal mines.Due to special mining planning,when the transportation roadway in panel 1513 of a mine working face is being drivaged,the panel 1511 is advancing outside a 40-meter wide gob,and the roadway is separated from the goaf and the small coal pillars are driven.Therefore,it is necessary to study the support problems under this special mining condition.This paper takes the practice of the transportation roadway driving along the goaf in panel 1513 of a mine as the research background.Using theoretical analysis and numerical simulation,and starting from the movement of overburden and the law of stress transfer in the stope,to analysis the influence of overburden strata fracture on the disturbance of the gob-side entry driving foward the other mining face and the influence of the propagation of mining stress on the surrounding rock stress disturbance along the roadway.Thereby revealing the large deformation mechanism of the roadway,and based on this to propose the corresponding surrounding rock control technology and test it on site.The main findings obtained are as follows:(1)The engineering characteristics of the research roadway were evaluated and analyzed.transportation roadway in panel 1513 belongs to the small coal pillar along the empty roadway under the conditions of large depth and high stress,strong mining in the separated goaf area and weak and fragile roof.Many unfavorable factors are superimposed on each other,which makes the roadway maintenance difficult.(2)The long-term deformation mechanism of the space-separation pressure mechanism and the long-term deformation mechanism affected by mining.Due to the gradual instability of the panel 1511,the unbreaking key layer in the 40 m wide shortwalled goaf caused continuous deformation along the empty roadway below it.In this process,the stress caused by the mining is in the space transfer and the secondary overburden stress distribution of the overburden in the shortwall goaf first causes stress disturbance to the roadway.The roof of the roadway along the empty road gradually descends with the mining,resulting in the instability of the large structure along the empty roadway.And through simulation,the deformation of the roadway in the range of 72m-99 m is obtained,and the deformation is stable after 108 m.(3)A reasonable coal pillar width of 6m is obtained by simulation,and the stress evolution characteristics of the wide coal pillar roadway are analyzed.The roadway heading distance from the panel 1511 is 55 m ahead of the 99 m lag,which is the serious impact zone of mining-boring stress superposition.The solid coal of the roadway is affected by high stress fluctuations,and maintenance is particularly difficult.(4)The principle and control technology of gob-side entry driving foward the mining face separate by a goaf are proposed.The roadway is divided into three sections: driving foward the mining mining section,the severely affected section and the far mining section,which should be segmented and managed.A new technology for strengthening control of surrounding rock in thick layer and high strength bearing ring for large deformation of surrounding rock in mining roadway is proposed,and parametric analysis and support effect verification were carried out through simulation.On the basis of the high stress fluctuation characteristics of the coal seam of the roadway that seriously affects the roadway,the integrated technology of pressurerelieving and anchoring is proposed.By constructing a high-strength bearing ring in the shallow part and decompressing the borehole in the solid coal gang,the dual functions of “shallow fortification” and “deep pressure relief” of the surrounding rock of the roadway are formed.The numerical simulation shows that the deformation of the roadway after pressure relief and anchoring is significantly reduced,and the optimum hole depth(10m)and effective row spacing(0.6~0.9m)of single hole pressure relief are clarified.