Study On The Damage Constitutive Model Of Fractured Rock Mass Considering Hydromechanical Coupling Effects

Rock rupture under hydromechanical coupling is a main theoretical problem in the disaster prevention of rock mass engineering, correct recognition and master of the wall rock damage evolution under the joint effect of mining disturbance and water pressure would play a significant role in deeply revealing the mechanism of geology disaster and realizing advanced alarm. Based on the laws of cracks propagation evolution, this article has analyzed the brittle failure mechanism of rock mass and established the fracturing rock brittle constitutive model, and the main works include the following aspects:(1) Through combining extended finite element with interaction integration, the process of compressively-sheared fracture of rocks with pre-existing fractures and the generation of wing cracks was simulated, and thus the evolution laws of wing cracks propagation were analyzed and researches on the influence of fracture spacing on stress intensity factor, stress field intensity and interaction between fractures were carried out.(2) Targeted at the defect of liner sliding crack model, the curve sliding crack model was established, which deduced the wing crack propagation path equation. While taking closure effect into consideration, the fracture conditions for primary fractures was deduced. The characterization volume unit was introduced and the double period distributed fracture model was proposed. And considering the interactions between cracks, the pseudo-traction method was introduced to deduce stress field intensity of crack tip. And according to the circumferential tensile strain criterion, the judgment method for brittle damages of fractured rock mass was deduced. With the help of embedded FISH language, new methods were programmed, and the characteristics of wall rocks brittle damages under different burial depths, coefficients of horizontal pressure, sectional forms, lengths of fracture traces, crack dips and friction coefficients of facture surfaces were studied.(3) According to the stress state of primary fractures under hydromechanical coupling, the fracturing laws of primary fractures under different stress conditions were studied. And through double curve simulated propagation path, the effect of seepage field on the propagation path was studied. And based on the pseudo-traction method, interactions between fractures under hydromechanical coupling hydromechanical coupling were studied, thus the condition of fracture rock masses brittle damages under hydromechanical coupling were deduced and the brittle damage characteristics of wall rocks under different osmotic pressures were revealed.(4) According to Betti’s reciprocal theorem, the flexibility tensor of equivalent fracture rock mass was deduced, the damage tensor of fracture rock mass was established, and the constitutive model for continuous anisotropic rock damage was constructed. According to Darcy’s law, the anisotropic permeability tensor caused by microcracks was deduced, the stiffness degradation method, permeability mutation formulas were established, and the constitutive model for brittle damage of fracturing rock mass under hydromechanical coupling was constructed. Secondary development and numerical realization with constitutive model as the foundation have verified the reasonability of the new model.