Abstract:

The deformation characteristics of bridge when metro tunnel closely crossing are very important. Hence, the influence of the construction of a tunnel on South Extention of Shenzhen Metro Line No. 5 on adjacent bridge pier #1 of Xinghai Avenue Viaduct is numerically simulated by FEM. The results show that: (1) The settlements of the upper parts of both side are the same, and the maximum settlement occurs on the right side of the tunnel. (2) The closer the bridge structure to tunnel excavation face, the larger the influence. (3) When the distance between pile and tunnel excavation face L is 7D, where D is span, the bridge pile begins to be affected by the tunnel construction. (4) When L=3D, the settlement rate of the piles increase significantly. (5) The vertical settlement deformation of the bridge pile above the tunnel is the largest, and the settlement increases with the buried depth increase. (6) The displacement direction of upper part of bridge pile goes along tunnel, and that of lower part of bridge pile goes opposite to the tunnel; and the extreme value of transverse displacement decreases with the distance between bridge pile and the tunnel increase. Finally, the deformation control standard for bridge is put forward by using the AHP method, and some suggestions are proposed to reduce the settlement deformation. The tunnel had been successfully passed through the viaduct, which verifies the rationality of analytical results.

Key words: mined tunnel, closely crossing, mining method, bridge pile, FEM, settlement displacement, AHP