Analysis of the properties of seepage rate and seepage force around tunnel circumference under the groundwater table

The threat of seepage to the stability of underground structure has always been remarked by a number of experts, and there engineering subjects collapsed because of the effect of seepage force. Some pursuers on the seepage have got invaluable results to solve the problems developed by the seepage force. In this paper, the author has reviewed the analytical solutions of the inflow, the hydraulic gradient and the seepage force have been obtained, and then described the importance of seepage to the stability of tunnel; the numerical analysis by Midas GTS has been also used to simulate the seepage, and illustrated the distribution of seepage rate around the tunnel circumference, and analyzed the effect of the tunnel depth, the space and the relative location on the distribution and the maximum values of seepage rate along the tunnel circumference. Finally, based on the Darcy's law the most instable location induced by the seepage force along the tunnel circumference has been represented for the single tunnel and the twin-tunnel, and the application range of the analytical expression has been also discussed, which will be advantage to the tunnel construction and reinforcement.