Study On Micro-Effect Of Mechanical Characteristics Of Coal-Bearing Sandstone

The development and improvement of rock mechanics theory has promoted the progress of coal mine production technology for a long time.Coal is an important component of China's energy structure,and the degree of mastering the physical and mechanical properties of rock mass is crucial to scientific mining and safety technology during production.However,there is a lack of integration of systematic means to automatically identify the physical and mechanical properties of rock strata in-situ and technology and method of intelligent decision-making in the strength and stability evaluation of coal and rock mass.Therefore,the microstructure effect of strength in sandstone of coal measures was studied in order to provide basic data for intelligent testing of mechanical parameters such as strength of coal and rock mass in this paper.The sandstone in Jining No.3 Coal Mine,Dongqu Coal Mine and Xinqiao Coal Mine in the Permian Shanxi Group was taken as the research object.The mineral composition and microscopic structure of different types of sandstone were obtained through X-ray diffractometer and polarized light microscope,and the microstructure characteristics of different kinds of sandstone were analyzed,including size and shape of particles,contact type,structure and composition of rock,composition and type of cement.The physical mechanics test system for rock was used to obtain laws of stress-strain curve of different types of sandstones and characteristics of mechanical parameters with micro changes was discussed.The results showed that the strength,elastic modulus,cohesion and friction coefficient of sandstone of coal measures increased with the increase of quartz and particle contact,and decreased with the increase of clay mineral.The mechanism of types of particle contact and cementation on the physical and mechanical properties of sandstone of coal measures was revealed.Through the parameters of acoustic emission signals and RA value,the failure characteristics and the spatial evolution of crack were obtained.Based on the results of uniaxial compression test and acoustic emission test,the damage evolution equation and damage constitutive model for strength of sandstone were also established.These results can provide a useful reference for the research and development of intelligent in-situ testing system for coal and rock mass parameters.