Study Of The Energy Dissipation And Crack Evolution Coupling Mechanism In Static Loading Of Coal-rock-like Composite Materials Subjected

Coal is the absolute foundation and important support for the sustainable development of China’s economic.As coal mines in many parts of China gradually enter the deep mining stage,the accompanying coal and gas protrusion,impact ground pressure and many other dynamic hazards seriously restrict the mine production safety.In this paper,three types of coal-rock composite models were prepared based on the geological conditions of a high gas mine seam in Heshun,Shanxi Province.The mechanical and acoustic emission characteristics experiments of coal-rock composite specimens under uniaxial loading conditions were carried out by combining energy and fractal theory,and the following results were obtained.(1)The coal-rock composite specimens were prepared by the self-developed quantitative preparation system of coal-rock-like material specimens.To obtain the full stress-strain curve,damage pattern,compressive strength,peak strain and elastic modulus variation characteristics of different coal-rock composite specimens.Uniaxial compression mechanical property experiments were carried out with coal-rock composite specimens under different combination methods(2)The crack generation,extension,development and penetration behavior of different coal-rock composite specimens during the full stress-strain process were analyzed using a high-definition camera monitoring system.The "box-correlation" fractal dimension integrated analysis software based on MATLAB was written to process the crack evolution images and calculate the fractal dimension of different coal-rock composite specimens at different stress stage.The development degree of fracture network in the process of static load rupture of the specimen is quantitatively described.(3)The acoustic emission behavior of coal-rock combination deformation and damage process under different combination conditions was monitored by acoustic emission signal acquisition system.The evolution of crack image of coal-rock combination specimen was combined with the inversion of crack progressive expansion characteristics by using acoustic emission localization events.The evolution relationship between stress change and acoustic emission parameters and crack progressive expansion characteristics during deformation and damage of coal-rock combination was further analyzed.(4)Based on the energy theory,the energy conversion law,energy storage and energy dissipated characteristics during uniaxial compression deformation damage of different types of coal-rock composite specimens are studied.The damage mechanism of coal-rock composite specimens and the coupling law of crack progressive evolution under energy-driven conditions are analyzed.The deformation damage characteristics of coal-rock systems in engineering practice are further discussed.Through the above research,this paper analyzed the acoustic emission behavior,damage morphology during the static load rupture of different types of coal-rock combinations and the crack progressive evolution law under energy-driven conditions,which provided important theoretical support for the prevention and control of dynamic mine disasters and other field engineering practice problems.