Study On Nonlinear Seepage Law Of Mining Broken Rock Mass

The instability for the flow of the water in the broken rock affected by the mining may result in some dynamical disasters,so the dynamical study on the flow in the broken rock is of great theoretical significance and application prospect.The dynamical behaviors of non-Darcy flow in the broken rock are investigated in detail based on the seepage experiments of the broken rock,the nonlinear dynamic theory and the numerical analyses.The analysis results and new research ideas formed by the thesis are as follows:(1)Relying on water flow experiments on broken rocks in the following three categories,the sandstone,the coal langue and the limestone,an equation about the non-Darcy seepage in the broken rock is obtained considering the fining and the crushing of the solid grains,and the rules of the seepage properties varying with the porosity are also presented.(2)The nonlinear dynamical behaviors for the systems of the non-Darcy water flow and the comprehensive gas flow in the broken rock are studied respectively;furthermore,the characteristics of the equilibrium states in these two flow systems are analyzed comparatively.By the successive low relaxation iteration method of difference,the numerical analyses to the stability of the dimensionless equilibrium state have been carried out,and the results indicate that with the changing of the parameter of the non-Darcy seepage there are a saddle–node bifurcation and a fold catastrophe.Then,the standard potential function about the generalized state variable,namely,the dimensionless seepage velocity has been put forward responding to the fold catastrophe in the flow system of the broken rock.(3)According to the effective stress principle and considering the motion of the solid framework and of the fluid simultaneously,the governing equation of the stress field involving the seepage variables and the governing equation of the seepage field containing the volume strain of the stress field have been developed,accordingly,the nonlinear dynamical equations of the coupled stress field and seepage field have been obtained.Then,the method and condition of decoupling the equations have been investigated and a conclusion has been drawn that under the condition confined laterally and when the stress boundary value varies with the time the equilibrium equation of the stress field can not be decoupled.(4)The dynamical equations of fluid and solid coupling for the non-Darcy flow of one dimension have been developed when the rock-fill in gob area transits from the naturally piled state to the stably suppressed state,and the dynamical responses have been given when the boundary stress tends to its stable value,moreover,these responses have been compared with the ones corresponding to the decoupled system.