Study On Seepage Characteristics And Engineering Application Of 3D Reconstruction Of Coal Fracture Slurry

The roof and wall of the high mining face often fall,which seriously affects the safety of coal production.Around the core of the research on the prevention of large mining height,the CT scanning test is carried out to study the internal micro fracture structure.The vinyl acetate ethylene copolymer emulsion(VAE emulsion)is used to modify the cement based materials,and a composite grouting material suitable for large mining height and anti film treatment is developed.The research provides theoretical support and engineering reference for the development of grouting reinforcement technology of large mining height anti sheet.The main work and research results are as follows(1)The mechanical properties test of coal body and 3D reconstruction analysis of CT scanning were carried out.Through uniaxial compressive strength test and splitting tensile strength test,the mechanical properties of coal and rock are studied,and the compactness is explored by combining with acoustic emission test.Through CT scanning and three-dimensional reconstruction technology of coal body,the internal pore fracture structure is extracted and analyzed.The results show that the coal quality of 14030 working face is relatively hard,the coal seam endogenous fractures are relatively developed,and the fractures present continuous "sheet" shape,which is the weak plane of coal body under stress,and it is easy to expand and destroy when disturbed.(2)Using VAE emulsion to modify cement based materials.The compressive strength and flexural strength of VAE modified Portland cement and aluminate slurry,as well as the micro scanning test of interface transition zone between slurry and coal were carried out.The results show that the VAE emulsion has a significant effect on the compressive strength and flexural strength of cement based slurry.The addition of VAE emulsion can effectively reduce the crack width in the interface transition zone and improve the bonding performance between the slurry and the coal surface.(3)The simulation experiment of composite slurry grouting in regenerated coal body was carried out,and the micro seepage characteristics in the inner part of the stone body were analyzed combined with CT scanning.VAE modified cement-based slurry can fully fill the pores of recycled coal,and the addition of polymer makes fine coal particles cemented together.Through numerical simulation,it is found that with the decrease of particle size of regenerated coal,the effective seepage channels in pores are not developed,and the development of slurry streamline changes from concentrated continuous bundle to short and dispersed state.(4)Industrial test was carried out to study the practicability of grouting reinforcement technology and VAE modified grouting material with large mining height and long distance.Large mining height and long distance flexible grouting reinforcement technology has significant reinforcement effect on fractured coal seam,effectively reducing the phenomenon of coal wall spalling,and has significant economic benefits.This paper contains 64 figures,11 tables and 96 references.