| The gas control mode of "one roadway multi-purpose,joint control and continuous mining" has been widely used in the gas control of deep coal seam mining because of its fast control speed and low consumption cost.The gas comprehensive control roadway in this mode is often arranged between two coal seams and is located in the roof of the underlying coal seam.Due to the influence of the strong mining of the underlying coal seam,the surrounding rock of the roadway is seriously deformed and damaged,which is difficult to meet the needs of normal ventilation and work.In view of this,how to maintain the stability of roadway surrounding rock and realize multi-purpose of one roadway is one of the difficult problems to be solved urgently.Taking the roof gas comprehensive treatment roadway of 17191(1)working face of Pansan Coal Mine as the engineering background,the evolution law of the overburden structure of the deep mine stope is studied by comprehensively using the methods of laboratory test,numerical simulation,theoretical analysis and field industrial test,the deformation and failure characteristics and instability mechanism of the surrounding rock of the roof roadway of the deep mine stope are revealed,and the advanced presplitting and pressure relief control technical scheme of the surrounding rock of the roof roadway of the deep mine stope is put forward and formulated.The following conclusions are obtained:(1)The evolution law of overburden structure in deep mine stope is revealed.After the mining of the working face,the rock stratum on the right side of the goaf forms a long arm "F" type suspended roof structure.When the working face is pushed to the stoping line,the rock stratum 43 m above the working face forms a separation layer with a width of 5mm and a length of 60 cm.The suspended roof structure on the right side of the goaf gradually changes from a long arm "F" type to a medium and short arm "F" type.The overburden of the working face presents a "upper three zones" zoning,in which the height of the caving zone is about 7m,the height of the fracture zone is about 38 m,and the rock stratum collapse angle is 55 °.(2)The deformation and failure characteristics and instability mechanism of surrounding rock of roof roadway in deep mine stope are revealed.The maximum vertical stress concentration of the surrounding rock of the roadway side is located in the middle and upper part,and the deformation of the side is asymmetric.The side slope near the goaf is large.The maximum horizontal stress concentration of the surrounding rock of the roadway floor is located in the middle.The floor is mainly tensile failure,and the failure depth is 4.5m.After the excavation of the working face,the original concentrated stress around the roadway,the additional stress of the cantilever structure and the lateral mining pressure of the working face form a superimposed stress,which acts on the surrounding rock of the roadway,intensifies the plastic failure of the surrounding rock of the roadway,and further leads to the increase of the deformation of the surrounding rock.(3)This paper puts forward and implements the advanced presplitting and pressure relief control technology of surrounding rock in roof roadway of deep mine stope.Based on theoretical analysis and numerical simulation experiments,the optimal values of pressure relief height and angle are 49.9m and 80 ° respectively.After adopting the technical scheme under the optimal parameter combination,the transformation of the lateral suspended roof structure of the working face from medium and short arm "F" type to short arm "F" type is realized,the "transfer" channel of the lateral mining support pressure to the surrounding rock of the roof roadway is blocked,the loading effect of the cantilever structure and mining support pressure on the surrounding rock of the roof roadway is reduced,the stress concentration of the surrounding rock of the roadway is reduced,the stable bearing characteristics of the surrounding rock structure are improved,and the deformation of roadway surrounding rock is reduced.After the technology is applied to the field practice,the roadway section shrinkage is reduced by 34.3%,and the test effect is good.Figure 77 Table 5 Reference 112... |
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