Abstract: Based on the engineering practice of a river-crossing tunnel of the Hangzhou, a three-dimensional numerical model for the excavation of the shield tunnel at the bottom of the river was established. Based on principles of the fluid-solid coupling, the seepage field and the displacement field around the underwater tunnel were predicted and evaluated. The seepage field was distributed in a loophole shape within one time the diameter of the tunnel, and the maximum settlement value of the riverbed was on the right side of the double-lane tunnel. The actual variation of the monitored parameters during the excavation was explored, and there was a certain correlation among the shield thrust, the grouting pressure and the soil pressure. Finally, the control measures for the construction of the shielded tunnel at the bottom of the river were proposed.

Key words: tunnel, fluid-solid coupling, numerical simulation, tunnel excavation parameters, control measures