Study On Surrounding Rock Control Technology Of Twice Dynamic Pressure Roadway With Hard Roof Working Face Of Xiaojihan Coal Mine

The goaf roadway will not only be affected by the upper section of the stoping face,but also serve the upper section of the stoping face.It will be affected by the repeated stoping of two stoping works.Roadway deformation is strong and difficult to maintain,and existing research results cannot effectively guide engineering practice problems,so most engineering problems are still solved by experience.Based on the engineering background of xiaojihan coal mine 11217 face return air lane,the in-depth study of abutment pressure and the change of lateral abutment pressure curve,lateral fracture location,affected by mining goaf roof section of the roadway surrounding rock deformation law in advance,advance section pillar working state,in summary xiaojihan coal mine roof movement and superposed stress rule,on the basis of fully mechanized face goaf are studied lateral movement law of top-coal and roof,analysis of roadway support and advanced supporting design,solve the problem of roadway support.The main results achieved are as follows:(1)The characteristics and abnormal law of dynamic pressure along goaf roadway are analyzed.When the dynamic pressure appears along the goaf roadway,the coal pillar is blown out in an instant,the coal body of the stoping side is rushed out,the roof Angle of the stoping side appears broken net and the roof falls violently,the single support area is inclined,and the working resistance of the hydraulic support has the changing trend of "rising-suddenly decreasing-rising".(2)The evolution process of roof structure along goaf roadway during two mining processes is analyzed.The lateral fracture of the basic roof forms a three-hinged arch structure after the first mining operation.During the second mining operation,the basic roof has been fractured in advance in front of the working face due to the influence of the working face's advance abutment pressure.The broken structure of the basic roof changes from the original consolidated hinged beam to a rotatable hinged beam.Therefore,after the secondary fracture,the roof pressure borne by the coal pillar will increase,and the lateral horizontal thrust of the coal pillar acting on the roof structure will increase,which will aggravate the overall deformation of the coal pillar and increase the displacement in the tunnel.(3)The deformation and instability mechanism of goaf roadway during two mining processes is studied.The influence of primary mining degrades the stability of surrounding rock and weakens the foundation to withstand the influence of secondary mining.The stress and displacement distribution of surrounding rock are controlled by the basic roof breaking structure of the working face during the secondary mining,and the deformation and failure of surrounding rock are more severe.(4)According to the stability control principle of surrounding rock along gob roadway influenced by two mining actions,the key control technology of surrounding rock of roadway under dynamic pressure is put forward,which is based on the flexible integral roof protection technology of fractured roadway roof with easy separation layer and the stress-relieving optimization technology of roadway roof with thick layer.The industrial test was carried out in the wind lane of the 11217 working face of Xiaojihan Coal mine.The observation results show that the deformation of roadway is effectively controlled,the deformation of roof is greatly reduced,no obvious separation occurs in the roof,the deformation and maintenance of roadway are fully satisfied with the use requirements of roadway,and the industrial test has been successful.There are 63 figures,12 tables and 62 references in this paper.