The pore water pressure and soil displacement induced by underwater shield tunneling: a case study

The underwater shield tunnel, differing from the land tunnel, is often inevitably constructed in soil with high water pressure and high crustal stress, which brings large construction risk, and the probable accidents may cause great economic losses and casualties, and therefore, it is indispensable to focus on the effect induced by shield tunneling on the soil around it. Based on the shield tunneling project of the Hangzhou Metro Cross-river Tunnel, according to the solution of excess pore water pressure produced by the horizontal and vertical concentration force inside the saturated soil, as to the excess pore water pressure induced by the additional thrust of the shield and the friction between the shield shell and the surrounding soil layer, its theoretical calculation method is obtained, and its distribution law is analyzed. As to uniform and composite strata, the thrust of the excavation face and shield friction was obtained. A three-dimensional numerical model was established, in which the support pressure of excavation face, shield shell friction, grouting pressure, overcut, and other factors were simulated, and the displacement distribution law of surface and subsurface soil induced by underwater shield tunnel construction was discussed.