Research On Unloading Creep Characteristics And Supporting Control Technology Of Surrounding Rock Of Large Diameter Coal Bunker

Deep rock mass engineering has been in the state of"three highs and one disturbance"for a long time,and it is very easy to produce hidden dangers such as large deformation,strong rheology,and serious damage to the supporting structure.Reasonable deformation and support forms are not adopted to deal with the expansion and deformation of surrounding rocks.It is very likely to cause disasters such as landslides and roof fall,splitting and fragmentation.How to ensure the stability and safety of these rock mass projects during construction and long-term operation has become an urgent problem to be solved.Based on the engineering background of the large-diameter coal bunker surrounding rock creep in the tenth mining area of Xinglongzhuang Coal Mine,this paper systematically studies the creep deformation instability mechanism and surrounding rock support of the surrounding rock of the coal bunker by comprehensively using indoor tests and numerical simulations.Control technology,analyze the stable state of the coal bunker under excavation and support,and propose corresponding support technical solutions to ensure the long-term stability of the coal bunker.The main research content and conclusions are as follows:(1)First,perform the mineral composition and microstructure characterization analysis on the coal and sandstone samples of Xinglongzhuang large-diameter coal bunker.The surface of the coal samples is relatively dense and smooth.The diameters of the primary micro-fractures are roughly the same,and there is no obvious roughness.Slipping is easy to occur,and large creep deformation is easy to occur under high ground stress;the internal minerals of the sandstone sample are well cemented,and the fine particles are wrapped by clay minerals.The whole is relatively complete.There are primary micro-fractures and the fracture surface has a certain degree of roughness.It is easy to produce friction and prevent relative slippage,which is easy to produce brittle failure and volume expansion.The meso-structure composition and structure difference have an important influence on the deformation and mechanism of the surrounding rock of Xinglongzhuang coal bunker.(2)The triaxial compression test of coal bunker surrounding rock under different confining pressure conditions and the triaxial creep test of coal bunker surrounding rock under different axial stress conditions were carried out.The basic mechanical properties of coal bunker surrounding rock and the creep mechanical properties of unloading confining pressure are studied,with emphasis on the analysis of the axial and lateral deformation laws,deformation rate laws,volume expansion laws,and expansion stress laws of coal and sandstone samples.(3)Using scanning electron microscope(SEM),three-dimensional scanner,etc.to perform microscopic characterization and analysis on the sample after triaxial creep damage,calculate the fractal box dimension of the microscopic surface roughness,and clarify the sample's characteristics after creep damage.The relationship between the internal microscopic morphology and the macroscopic fracture;the evolution characteristics of the standard deviation,the inclination angle and the aspect of the creep fracture surface of the sample are analyzed;the creep failure of the surrounding rock of the coal bunker and the microscopic dilatancy effect and the position of the crystal are summarized.The wrong movement is inseparable.(4)Using FLAC^3D numerical simulation software to simulate the evolution characteristics of the displacement and plastic zone of the large diameter coal bunker in Xinglongzhuang during the original excavation and support process,and analyze the coal bunker with different supports during the excavation and support process.The evolution law of the maximum displacement,plastic zone and stress in the form of the coal bunker;analyzes the influence of the coal bunker on the adjacent shaft under the optimal coal bunker excavation and support conditions and under the unsupported conditions;proposes the larger deformation of the coal bunker Take corresponding strengthening support measures to ensure the overall stability and safety of the surrounding rock of the coal bunker.