Abstract
It is reported that the amount of the seepage water measured in an undersea tunnel has been decreasing. The decrease of the seepage water is preferable in the view of tunnel maintenance. However, it can change the pore water pressure in the surrounding ground and reduce the safety of the lining. Therefore, we evaluate numerically soundness of the undersea tunnel by the soil-water coupled finite element analysis. We assume that the permeability decrease in surrounding ground is the reason for the decrease of seepage water and consider three cases. It is concluded that there is possibility that the permeability leads change of pore water pressure or expansion of plastic zone.