Study On Surrounding Rock Deformation Mechanism And Control Technology Of Gob-side Entry Driving In Deep Mine

With the gradual depletion of shallow coal resources in China,the mining depth of the mine increases gradually,and the surrounding rock shows obvious rheological large deformation state.In order to maintain the stability of the coal pillar,the width of the coal pillar of gob-side entry driving in deep mine also increases,so that the gob-side entry driving is forced to be arranged in the mining stress increasing area,and the support problem becomes increasingly prominent.Based on the 1126(1)track alignment in Guqiao Mine,this paper studies the temporal and spatial evolution law of surrounding rock stress,fracture and deformation in gob-side entry driving,driving and stoping process through theoretical analysis,numerical simulation,similar material test and field monitoring(1)The mechanical model of coal mass under lateral mining is established,and the stress distribution equation and plastic zone development depth under lateral mining are solved.The influencing factors of the mechanical model of coal mass stress distribution are analyzed.The mechanical model of working face under advanced mining is further developed,and the stress distribution equation of 1126(1)working face and the plastic zone development depth of gob-side entry are solved.(2)Through the numerical simulation research,it can be seen that the plastic zone and stress distribution of surrounding rock of gob-side entry in deep mine are obviously asymmetric.The damage degree of surrounding rock on the side of gob side pillar is greater than that on the side of solid coal.The deformation and damage degree of surrounding rock is roof>solid coal>coal pillar>floor.After the roadway roof and two sides are reinforced,the plastic zone and stress distribution asymmetry of surrounding rock of gob-side entry are reduced,and the deformation and failure degree of roof and two sides are reduced.However,because the floor is not supported,more deformation energy is released through the floor,and the floor heave is increased.At this time,the deformation and failure degree of surrounding rock is as follows:floor>roof>solid coal>coal pillar.In the mining stage of working face,the influence range of advance mining of gob-side entry is about 60 m,the influence of advance mining of solid coal is greater than that of coal pillar,and the plastic zone and stress distribution asymmetry of surrounding rock of roadway increase.(3)It is found by the similar material experiment that after the mining of adjacent working face,the surrounding coal and rock mass appear overall subsidence,the floor has appeared a large range of cracks,the integrity of surrounding rock is destroyed,the floor of goaf rises,the cantilever beam structure appears at the edge of goaf roof,and the maximum vertical stress of surrounding rock of gob-side entry is located in the cantilever beam structure above the coal pillar.After driving along the goaf,with the increase of the model confining pressure,the surrounding rock of the two sides of the roadway is embedded into the floor,the floor of the roadway rises relatively,the cantilever beam structure appears cracks and develops gradually,which eventually causes the cantilever beam structure to disappear,and the maximum vertical stress of the surrounding rock of driving along the goaf is transferred from the top of the coal pillar to the bottom of the solid coal.(4)According to the engineering conditions and stress distribution characteristics of 1126(1)track along gob driving roadway in Guqiao Mine,the influencing factors of surrounding rock stability are analyzed.It is considered that the floor heave of 1126(1)track along gob is caused by the coupling of multiple factors such as high ground stress,lateral mining,poor lithology of surrounding rock and in-situ stress direction.The asymmetric support scheme based on anchor mesh cable is proposed,and the side anchor cable is added to strengthen the coal pillar side roadway Road support.Through the analysis of 1126(1)deformation observation data,it is concluded that the designed roadway support scheme can effectively control the roadway deformation in the excavation stage,but due to the poor lithology of the floor and no support,the roadway floor heave is more serious,so we should go undercover in time.In the mining stage of this working face,the influence range of advanced support is 59.5?66.2 m,so the advanced support should be carried out in time before 70 m in front of the working face to ensure the safe production of the working face.The research results of this paper reveal the spatial and temporal evolution law of surrounding rock stress,deformation and plastic zone of gob-side entry driving in Guqiao Coal Mine,provide theoretical and technical reference for the support of this kind of roadway,and ensure the safe and efficient mining work of 1126(1)working face.Figure 61 Table 10 Reference 93...