Implementation and engineering application of an improved rotating smeared crack model in rock mass fracture

By improving the original transverse isotropic constitutive model of FLAC3D and secondary development, the theory of original smeared crack model was modified and introduced into the simulation of progressive fracture of rock mass from the research focus of concrete. Rotating smeared crack model is adopted, which means the smeared crack surface inside element changes every moment with the redistribution of stress. The maximum tensile strain theory was defined as the damage criterion of mesoscopic element to establish degeneration principles. The dynamic strike, dip direction and dip angle of the smeared crack surface were deduced in FLAC3D, and the synergistic relationship between the elastic modulus, shear modulus and tensile damage was quantified, through which programming was realized the first time using finite difference method. The crack propagation path and lap mode of rock specimen under three groups of tension-shear test conditions were studied and analysed. The simulation results match well with experiments by predecessors, which demonstrates validity and feasibility of this new method. Moreover, the proposed model was also applied to investigate the slope excavation of Dagangshan Hydropower Station in China. The whole process of continuous deterioration and expansion of damaged zone caused by unloading stress was studied. And overload test was performed to calculate the safety factor, showing good effect.