The Study On Damage Rheological Model Of Fractured Rockmass And Its Engineering Application

The study on the mechanics and time-dependent feature of fractured rock mass is always an important subject of rock mechanics and engineering. Based on the theoretical method of rock damage mechanics, rock rheological mechanics and numerical calculation, this paper makes a preliminary study on the damge and rheology coupled model of fractured rock mass and its engineering application.First, according to the structural characteristics of fractured rock mass and the geometric damage theory, we cite a second-order damage tensor to describe the deterioration of rock mass due to cracks. Taking the crack area, direction, space and density 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. The Nishihara model is taken as the basic model to study the time-dependent characteristics of rock mass. And its one-dimensional constitutive equation is transformed into three-dimensional form. Eventually, by introducing the second-order damage tensor into the rheological constitutive equation on the basis of the equivalent strain hypothesis, the three-dimensional viscoelastic-plastic damage constitutive equation is deduced.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.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 long-term stability and security of underground cavern group.