Abstract: River dredging excavation is an unloading process, which is easily to cause deformation of the shielded tunnel below. Therefore, the influence of river dredging excavation on the deformation of the shielded tunnel section of the rail transit Line No. 2 and the adjacent subway stations is studied by using the three-dimensional finite element method (FEM). The results show that the lateral displacement and the settlement of the tunnel structure are easily to be caused when the river dredging excavation is located on the side of the shielded tunnel. When the river dredging excavation is directly above the shielded section of the rail transit, the tunnel buoyancy caused by the soil excavation in this area is the largest. The overall stiffness of the station structure is much larger than that of the shielded structure, so the deformation of the main structure of the station is much smaller than that of the shielded structure during the river dredging excavation. The influence of the river dredging excavation on the deformation of shielded tunnel and the subway station can be effectively reduced by adopting measures such as portal soil reinforcement, “Tofu Cutting” excavation and the river bottom counterweight.

Key words: mucky soils, river dredging excavation, portal soil reinforcement, shield tunnel excavation, numerical simulation