Flow characteristics after water inrush from the working face in karst tunneling

摘要

In order to investigate flow characteristics after water inrush from the working face in process of karst tunnel construction, numerical calculation for two class case studies of water inrush is carried out by using the FLUENT software on the background of Qiyueshan tunnel. For each class water inrush from the tunnel face, five cases under different water-inrush velocity are simulated and researched. Three probing lines are selected respectively in the left tunnel, cross passage, right tunnel and in the height direction of the tunnel centerline. The variation characteristics of velocity and pressure on each probing line under the five water-inrush velocities are analyzed. As for the selected four groups probing lines in the tunnels, the change rules of velocity and pressure on each group probing lines under the same water-inrush velocity are discussed. Finally, the water flow characteristics after inrush from the tunnel face are summarized by comparing the case studies. The results indicate that: (1) The velocity and pressure change greatly at the intersection area of the cross passage and the tunnels. (2) The velocity nearby the tunnel side wall is the minimum, while it is the maximum in the middle position. (3) The pressure value of every cross section in the tunnels is basically fixed. (4) As water-inrush velocity increases, the flow velocity and pressure in the tunnels also increase. The former is approximately proportional to their respective water-inrush velocity, while the latter is not. The research results provide a theoretical basis for making scientific and rational escape routes.