| In recent years,although the technology of gob-side entry driving has effectively solved the tense situation of coal mining replacement,the deformation and failure of surrounding rock of gob-side entry(strong mining roadway)caused by mining is still a key problem to be solved urgently in coal mine production.Affected by strong mining,the surrounding rock of gob-side roadway is easy to deform and destroy,and the existing control technology of surrounding rock of gob-side roadway can not solve such problems well,which seriously limits the safe and efficient mining of coal mine.Therefore,it is necessary to carry out exploration and research on the problems of poor stability of surrounding rock and roadway support caused by strong mining.Based on the engineering background of gob-side entry driving of A110607 return airway in Wenjiaba Coal Mine,this paper makes an in-depth study on the stability control of surrounding rock of strong mining roadway caused by gob-side entry driving through field investigation,laboratory test,theoretical analysis,numerical simulation and field industrial test.The main conclusions of this paper are as follows:(1)Through on-site investigation,the roof subsidence and partial side of the roadway are more serious.The site uses drilling to peep.There are a large number of macroscopic visible cracks in the surrounding rock at the top,and the integrity is poor.Under the A110607 return air roadway,the A110705 coal mining face is under mining,which is strongly affected by mining stress.The deformation and failure of roadway roof and coal pillar side are serious,which is the key factor of roadway deformation and failure.(2)By establishing the mechanical model of the instability of the arc triangular block and the mechanical model of the surrounding rock structure of the gob-side entry driving along the small coal pillar,the conditions of the instability of the triangular block structure and the location of the best fracture line are analyzed.Through theoretical calculation and numerical simulation,the reasonable coal pillar width is 3 m.(3)By means of theoretical calculation and numerical simulation,the influence of roof cutting height and roof cutting angle on the movement law of roof overburden and the stress distribution of small coal pillar in goaf is studied.The best roof cutting parameters are determined as 8 m of roof cutting height and 15 ° of roof cutting angle.Through the field blasting test,the optimal hole spacing is determined to be 800 mm.(4)Through numerical simulation software,the stress distribution characteristics and displacement evolution law of surrounding rock in gob-side entry driving with or without roof cutting are studied.The results show that in the process of gob-side entry driving,the peak stress in the solid coal wall and the small coal pillar after roof cutting decreases by 17.6% and 10.7% respectively compared with that before roof cutting.After roof cutting,the roof and floor convergence and the convergence of the two sides of the roadway are reduced by 40.7% and 33.3%respectively.(5)According to the specific situation of A110607 return airway,the con trol technology strategy of strong mining roadway is given,and the ’ unloading-solid-support ’ collaborative control technology scheme is proposed.The slurryratio optimization test was carried out indoors,and the optimal slurry ratio sc heme for grouting reinforcement was selected.Through field application,the a mount of roof and floor movement in the roof cutting section of the gob-side roadway is reduced by about 38% compared with the uncut section during theheading of the mining roadway,and the deformation of the two sides of the roadway is reduced by about 44% compared with the uncut section,indicating that the scheme has a good control effect on the strong mining roadway. |
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