Damage constitutive model and mechanical properties of jointed rock mass under hydro-mechanical coupling

The damage evolution law and mechanical property weakening mechanism of jointed rock mass under hydro-mechanical coupling are important scientific problems in deep rock mass excavation. In this paper, the min-eral composition of rock specimens was analyzed, and the distribution law of nuclear magnetic resonance T2 spectrum of granite under different axial stress was studied. Then the mechanical properties of jointed rock samples under triaxial stress and seepage pressure were studied. Based on the analysis of the stress field at the joint tip, the damage model of the jointed rock mass was obtained. Furthermore, the tensor of damage variables was analyzed, and the stress intensity factor under seepage pressure was calculated. The seepage pressure promotes the damage evolution process of jointed rock mass specimens and accelerates the strength failure of jointed rock mass specimens. The damage constitutive model of jointed rock mass under seepage pressure was established and verified. Based on the weakening law of seepage pressure, the developed hydro-mechanical coupling constitutive model was customized and imported into FLAC3D with the calculation function of the Mohr-Coulomb constitutive model as the compilation template. A three-dimensional numerical simulation model of underground rock mass engineering was established to analyze the stability of rock mass with different joint dip angles. For the surrounding rock with the dominant angle of 85 degrees in the mine, its stability is poor, and the support needs to be strengthened.