Abstract: Due to various construction effects, the existing box culvert will have excessive deformation and cracking when a shielded tunnel boring machine (TBM) passes through. To analyze the deformation pattern of the existing box culvert and its relationship with the cracking when the TBM passes underneath, this paper presents a section of Changzhou Line 2 a case history. The finite element method was used to simulate the entire process of the shielded tunnel excavation passing through the existing box culvert with the onsite monitoring data and the cracking observation of the box culvert. The numerical analysis also considers the effects of construction parameters such as grouting amount, soil pressure and friction on the deformation and cracking. The results show that the cracks are controlled by the displacement in the excavation direction and the vertical displacement. The secondary grouting range has the greatest influence on the vertical displacement, and with the increase of the secondary grouting range, the settlement decreases by 84.3%; The friction has the greatest influence on the displacement in the excavation direction, and with the increase of friction, the displacement in the excavation direction can increase by 55%;The increase of soil pressure will decrease its vertical displacement, and then increase the displacement in the excavation direction.

Key words: Shielded Tunnel Excavation, Box Culvert, Displacement, Crack, Numerical Analysis