| At present,China is rich in thin and very thin coal seam resources,of which 84.2% of mining areas have thin coal seam,especially in the southwest region widely distributed.Recently,with the increase of mining intensity,the mining reserves of thick and medium-thick coal seams in many mines are decreasing day by day.In order to ensure the balance of mine production capacity and prolong the service life of mines in various regions,improve the resource recovery rate and maximize the utilization of resources,efficient mining of thin coal seams has become a key problem to be solved urgently.Therefore,it is of great significance to attach importance to thin seam mining for promoting the development of China's coal industry.Generally,the geological environment of coal mine is complex,and the uneven large deformation and destruction are often caused during the excavation of coal and rock roadways.Therefore,based on the support and stability problems faced by typical thin seam roadways in southern China,this paper systematically studies the evolution law of uneven deformation,fracture and expansion of thin seam roadways and the key points of surrounding rock support control by using the methods of field monitoring,rock mechanics test,theoretical analysis and field application test.(1)According to field investigation,the development characteristics of surrounding rock fracture structure under stress disturbance in thin coal seam roadway are analyzed,the mechanism of uneven deformation and failure of coal and rock roadway is discussed,and the essence of uneven deformation characteristics of typical coal and rock mass is analyzed from macro-meso and hydration tests.(2)With the help of experiment and theoretical analysis,the anchor bolt resistance model of fracture structural plane of coal-rock combination through inclination angle is established,and the main factors affecting the anchor resistance are compared.Through the formation of anchor system with anchor and coal-rock mass,the determination of the optimum anchor angle of bolt is analyzed,and the test verification is carried out.The results show that the theoretical model of bolt is in good agreement with the test results.(3)A series of mechanical tests were carried out on coal-rock assemblages,loose coal-rock assemblages,inclined coal-rock assemblies and "bolt + coal-rock" anchorage assemblies.The failure characteristics of all kinds of samples in the whole process of failure were discussed,and the non-linear failure essence caused by rock differences was analyzed.(4)The characteristics of circumferential strain and infrared thermal image of bolt penetrating inclined coal-rock combination are studied.It is found that the overall coordinated deformation of bolt penetrating inclined coal-rock combination specimen is poor during the process of loading failure,i.e.,the non-linear and non-uniform failure of composite specimen.The abrupt change coefficient of temperature in the failure process of coal-rock assemblage system is also established by infrared thermography.(5)For the non-uniform deformation of thin coal seam in Baise mining area,the principle of stability control is put forward.The influence of slip between coal and rock mass in coal and rock roadway,normal stress and surface characteristics of interlayer interface,properties of interlayer filling material and filling thickness on shear strength of coal-rock interface are considered comprehensively.Finally,on the geological environment of the test roadway,the optimization scheme is tested in the field,and the convergence deformation of roadway surrounding rock and the stress of supporting bolt are monitored dynamically in real time.Combined with the monitoring data,the supporting effect is verified and evaluated. |
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