True Triaxial Test On Mechanical Properties And Energy Evolution Of Deep Coal-rock Mass

Under the influence of deep coal-rock roadway excavation and working face mining,the coal-rock roadway wall is usually under the joint action of lateral unloading and vertical stress concentration,and the mechanical strength of surrounding rock is low,the deformation is large,and the stability of surrounding rock is difficult.Therefore,only by thoroughly mastering the true triaxial mechanical properties of coal rock mass under deep excavation and mining path can we reveal the deformation mechanism of deep coal-rock roadway wall and guide the weak links of surrounding rock control in deep coal-rock roadway.Starting from the definition of deep mining,this paper takes deep coal-rock assemblage as the research object.Based on the theoretical basis of rock mechanics,damage mechanics,thermodynamics and similarity theory,this paper comprehensively adopts the research method combining theoretical analysis,true triaxial rock mechanics test in laboratory and numerical calculation.The true triaxial mechanical properties and energy evolution law of coal and rock mass under deep excavation and mining path are systematically studied,and the following research results are mainly obtained:(1)True triaxial mechanical tests of deep coal and rock mass under excavation and mining path were carried out by using true triaxial electro-hydraulic servo loading and unloading test system,and true triaxial mechanical strength,failure characteristics and deformation characteristics of coal and rock mass with different coal and rock ratios and different dip angles of coal and rock interface were obtained.The effects of coal-rock ratio and coal-rock interface Angle on true triaxial mechanical properties and failure characteristics of coal-rock assemblage under deep excavation and mining path are revealed.(2)based on the combination of deep coal and rock excavation and stoping path test results of true triaxial mechanics,starting from the energy principle,the combination of deep coal and rock excavation and stoping path under the energy accumulation-dissipative characteristics in the process of deformation and failure,the introduction of energy dissipation ratio characterization of coal and rock combination energy evolution regularity in the process of test,The influence of coal-rock combination ratio and coal-rock interface angle on the energy evolution of coalbody is analyzed,and the damage parameters characterizing the damage characteristics of coal-rock coalbody are proposed.(3)Based on elastoplastic mechanics,damage mechanics and thermodynamics theory,considering the influence of plastic and damage interaction on mechanical properties of deep coal and rock mass,the elastoplastic damage constitutive model of deep coal and rock mass based on Drucker-Prager criterion is established,and the corresponding elastoplastic damage constitutive equation is derived.The numerical calculation of the elastoplastic damage constitutive model in 3DEC is realized,and the numerical calculation results are in good agreement with the experimental results.The research results provide a theoretical basis for numerical calculation of supporting parameters of deep semi-coal roadway.