Study On Mechanical Deformation Characteristics And Energy Evolution Of Marble Under Deep High Ground Stress

Based on the actual needs of shallow resource depletion,deep scientific research and exploration,and deep protection engineering construction,the necessity and inevitability of deep rock mechanics research are increasing.The occurrence environment of deep rock mass is complex and changeable,often accompanied by the problem of " three high and one disturbance." The difference between deep and shallow mainly comes from the depth of occurrence,that is,the problem of high ground stress.High confining pressure is a typical characteristic of high geostress.In order to study the effect and influence mechanism of confining pressure on the mechanical properties and deformation response of deep rock,the mechanical deformation response of deep marble under different confining pressures was studied by combining test and numerical simulation.Combined with energy analysis,the mechanism of rock failure process is analyzed from the perspective of strain energy evolution and energy damage variable.Using the advantages of numerical simulation,the supplementary research on the deficiency of mechanical test is completed.By using the grey correlation analysis method,based on the data of test and numerical simulation results,the significance ranking of the main influencing factors of deep marble energy index is obtained,that is,the correlation ranking of response sensitivity.The main research contents are as follows :(1)The basic physical and mechanical properties of deep marble were studied.Porosity test,polarization detection and sound velocity test are mainly carried out,which provide basic physical characteristic parameters for numerical simulation.The uniaxial and triaxial compression tests under different confining pressures were completed,and the relationship between confining pressure and mechanical deformation parameters of marble was obtained.(2)The influence of confining pressure effect on mechanical deformation response and energy evolution damage of marble is studied.Through the study of the influence of confining pressure on the mechanical deformation characteristics of marble,the influence of confining pressure on deviatoric stress-strain curve,the influence of confining pressure on elastic modulus and Poisson ’s ratio,and the influence of confining pressure on failure mode are obtained.Through the study of the influence of confining pressure on the energy evolution of marble,the evolution law and variation characteristics of confining pressure on each strain energy are obtained,and the influence law of confining pressure on energy damage variable is obtained.(3)The uniaxial and triaxial compression simulation tests under different confining pressures were carried out by PFC numerical simulation software.The influence mechanism of confining pressure effect on the sensitivity response of macroscopic mechanical deformation parameters to mesoscopic parameters and the sensitivity response law of mechanical deformation parameters to mesoscopic parameters are obtained,and the optimization of mesoscopic parameters of constitutive model is completed.(4)Using the crack statistics of PFC and the displacement-velocity field changes of particle elements,the influence mechanism of confining pressure on the macroscopic failure mode of marble is analyzed,and the relationship between confining pressure and energy damage evolution of marble is studied from the perspective of energy evolution.(5)Based on the data of test and numerical simulation results,the grey correlation method is used to calculate the correlation degree between the characteristic indexes of each physical quantity and the comparison indexes.The correlation relationship between confining pressure and strain energy is established,and the significance ranking of the main influencing factors of deep marble energy index is obtained.