Study On A Geometric Initial Damage Model And Its Applications In Numerical Simulations Of Geotechnical Engineering

The study on the mechanics feature of fractured rock mass is always an important subject of rock mechanics and engineering. Based on the theo retical method of rock damage mechanics, fracture mechanics, mechanics an d numerical calculation, this paper makes a preliminary study on the damg e and model of fractured rock mass and its engineering application.First, based on the research of former scholars,according to the structuralcharacteristics of fractured rock mass and the geometric damage theory, we cite a damage matrix to describe the deterioration of rock mass due to cracks. Taking the crack area, direction, space and density etc as the major influencing factors of the damage variable, we stack the damage contribution of groups of cracks on each section to describe the anisotropic damage approximatively. By introducing the damage matrix into the deterioration of rock mass constitutive model on the basis of the equivalent strain hypothesis, the deterioration of rock mass constitutive model based on Mohr-Coulomb criterion is deduced. we consider the production of secondery crack and rock bridge's transfixion based on Fracture Mechanics.and according to the deterioration of rock mass,damage evolution failure criterion are build.Taking FLAC3D Version2.1 as the development platform, we compile the above constitutive model on the VC++6.0 environment, and realize the secondary development of FLAC3D. The operation principles of secondary development program is also described. A criterion program of the damage evolution equation for fractured rock masses was compiled using the FISH language attached in FLAC3D. Combined with the procedure of initial damage constitutive model for rock mass, the program of the initial geometric damage and the damage evolution for fractured rock mass was further achieved.In the end, the surrounding rock stability of the underground cavern group of Shuangjiangkou hydropower station is analysed by using the development program. And the results are compared with the ones obtained from the computation with elastic-plastic model. According to the comparative results, the model is basically reasonable. Meanwhile, some rational suggestions are put forward for the stability and security of underground cavern group.