State of the art and trends of water-inrush mechanism of nonlinear flow in fractured rock mass

The state of the art of nonlinear seepage theories,non-Darcy flow tests and nonlinear flow numerical models of water-inrush induced by nonlinear flow in fractured rock mass are summarized according to the available data. It is found that both three flow fields,i. e. ,Darcy flow,the high-velocity non-Darcy flow and the turbulent flow,and three principal factors,i. e. ,Darcy flow of the water resource,the high-velocity non-Darcy flow in water-inrush channel and the influence of mining disturbances,exist together in the process of mining induced water inrush. This paper holds that non-Darcy flow in water-inrush channel,the unity of three dynamic flow fields and the stress disturbance characteristics of the three principal factors are quite important to the flow in fractured rock mass. Based on the above views,the trends of water-inrush in fractured rock mass have been put forward. Considering the three principal factors of mining- induced water inrush,the laws of the seepage in fractured rocks under different confining pressures,hydraulic gradients and flow rates will be researched according to the experiment and the field investigation. The aim is to establish a coupled model of Darcy equation,Forchheimer equation and Navier-Stokes equation with the effect of mining stress. The corresponding model will be studied by numerical method,which is proposed on the basis of coupling integral equa- tions of the weak form of the finite element and the finite volume technique. In the model,both the flow and the pres- sure boundaries of the Forchheimer flow zone are dynamic as time changes. In this way,the problems of the nonlinear seepage models in fractured rock mass can be solved effectively,and the complete flowing process of mining induced water-inrush can also be simulated reasonably.