Narrow Results

A new anisotropic damage model for rock is formulated and discussed. Flow rules are derived with the energy release rate conjugate to damage, which is thermodynamically consistent. Drucker–Prager yield function is adapted to make the damage threshold depend on damage energy release rate and to distinguish between tension and compression strength. Positivity of dissipation is ensured by using a nonassociate flow rule for damage, while nonelastic deformation due to damage is computed by an associate flow rule. Simulations show that the model meets thermodynamic requirements, follows a rigorous formulation, and predicts expected trends for damage, deformation and stiffness.

In order to research the seepage phenomena of one kind of granite materials, investigations on the seepage characteristics on the granite materials by experiments, numerical simulation and theoretical analysis had been carried out. A surrounding rock with an internal cavity, which would be filled with the TNT explosive charge and exploded, was taken as the research object. Firstly, a two dimensional cylindrical symmetrical mathematical model of dual porosity and dual permeability was built by taking into account of gas permeation in porous media, gas diffusion and heat conduction between gas and surrounding rock. And some related experiments of gas seepage in granite were carried out too, in which, the TNT explosive charge was exploded in the center cavity of the granite. Taking the detonation product CO as the trace gas, the amount of gas permeability and the arrival time of the gas seepage were obtained. Comparison with experimental results shows that the numerical simulation results are accurate and reliable. Then, based on the Darcy’s law, considering the influence of some major factors, like the rock fracture, the porosity and the permeability of the granite materials, analytical formulas of some important parameters of the research object, which mainly include the amount of gas permeability and the arrival time of the gas seepage, were derived. Meanwhile, the formulas were used to calculate the results in one of the experiments introduced before. The important parameters in seepage phenomena, such as the arrival time and the total volume of the seepage gas, calculated by these formulas compared very well with the corresponding experiment.