Analytical Solution for Non-Darcy Flow Induced Settlement of Shield Tunnel in Soft Soil

Leakage is one of the main diseases of subway shield tunnel in the saturated soft soil, and it is also the main cause of the long-term settlement of the stratum and tunnel. Seepage in the soil was assumed to follow the Slepicka exponential seepage model, while the seepage in the lining was assumed to follow the Darcy linear seepage model, and the analytical solution of the pore-pressure distribution of the soil around the shallow tunnel under the condition of non-Darcy seepage was derived. On this basis, the analytical solution of the tunnel settlement was further obtained. The correctness of the proposed analytical solutions were verified by case analysis, and the influence of non-Darcy seepage on the pore-pressure of soil around the tunnel and the surface settlement above the tunnel was further analyzed. The results show that the non-Darcy seepage index m has a significant impact on the pore-pressure distribution and surface settlement of the soil around the tunnel. With increasing the value of m, the pore-pressure of the soil around the tunnel is gradually reduced, and the surface settlement is gradually increased. The influence of non-Darcy seepage must be considered in analyzing the seepage of shield tunnel in saturated soft soil. This paper can provide some reference for the design and construction of similar projects.