Study of seepage field distribution and its influence on urban tunnels in water-rich regions

This paper presents a study of the spatial distribution of pore water pressure on urban tunnels in water-rich regions. Based on Harr's classical solution for unlined tunnels and the actual hydrological environment, a water pressure formula of the seepage field is derived by regarding the surrounding rock, grouting circle, lining, etc., as a complete system. The seepage model test system developed is applied to test the distribution of water pressure in the surrounding rock for an unlined tunnel and a tunnel that contains both a grouting circle and a lining. For the unlined tunnel, the degree of coincidence between the theoretical and experimental results is higher at a distance from the tunnel center than near the center of tunnel. For the tunnel with the grouting circle and lining, the theoretical solution tallies with the experimental results. The decrease in the permeability coefficient of the grouting circle or the degradation of lining permeability will cause the water pressure in the surrounding rock to rise, with the latter effect being more significant. However, the effect of changing the grouting radius on the tunnel seepage field is not obvious.