Study On Damage Constitutive Model Of Deep Fractured Rock Mass Based On Elastic Wave Propagation Tests

Recently,with the wide application of elastic wave testing technique for rock damage measuring,the research on damage mechanic characteristics of deep fractured rock mass based on the parameters related to elastic wave has already entered into the period of quantification.A large amount of research indicates that there are different propagation and fading characteristics of elastic wave through rock mass with different damage degree.Based on above content,following works have been done in this paper:?1?Obtaining the wave equation of elastic wave propagation through infinite elastic medium and fractured medium without thickness based on stress wave propagation theory,and then carrying out the theoretical derivation on transmission and refection rules of elastic wave passing single fractured rock mass with thickness and it with a single set of parallel fractures through the methods of discontinuous displacement and equivalent medium model,which lays the foundation for test programme design of elastic wave propagation characteristics through fractured rock mass under different loading methods.?2?Developing complete rock samples which can indicate mechanical properties of deep fractured rock mass under different loading methods and fractured samples with different crack quantity and inclined angle based on similarity theory and mix proportion test and with surrounding rock around deep buried tunnel at Jinping?hydropower station as prototype combining.According to the high stress environment,the complex stress state and difficulty sampling of the deep rock mass,experiments of elastic wave propagation characteristics with complete and fractured rock samples under conditions of triaxial compression and triaxial tension-compression is carried out by the true triaxial apparatus based on the theory of similarity,and the the confining pressure is 0.6MPa,1.2MPa,1.8MPa?simulating the high stress level of 20MPa,40MPa,60MPa by similarity calculation?before its ultimate state,investigating the change regulation of velocity and amplitude of elastic wave under pressure based on experiments and analyzing the influence of stress effect,crack quantity and crack distribution angle on elastic wave propagation characteristics as well.?3?Analyzing and comparing the macro damage process of complete and fractured rock mass based on the experiment of elastic wave propagation characteristics,investigating the crack initiation stress and extension length of macro cracks?damage?in fractured rock mass,by comparing the sensitivity of elastic wave velocity and elastic wave amplitude to the macroscopic damage evolution process of fractured rock mass,and carrying out quantitative research on macro damage process of fractured rock mass under different loading methods by the macro damage variable defined with elastic wave amplitude.?4?Starting the research on damage constitutive model of fractured rock mass based on the coupling of macro and micro cracks with the micro damage variable defined by statistical damage theory and macro damage variable defined by tensor processing with the theoretical foundation of equivalent strain principle,and comparing the stress-strain relationship of fractured rock mass in laboratory model test to testing data as well.?5?Finishing the establishment of macro and micro damage constitutive model in FLAC^3D based on the Mohr-Coulomb model in FLAC^3D,reproducing the experiment of elastic wave propagation characteristics in fractured rock mass under different loading methods with it and Mohr-Coulomb model,comparing its rationality and superiority,finally analyzing the damage region during the excavation of buried diversion tunnel at Jinping hydropower station based on it and comparing to field measuring data as well.