Influence of Shield Close-spaced Construction on Settlement of Bridge Pile and Protective Measures

During close-spaced tunnel construction passing through existing bridge piles, and based on the field measured data, the change rules of bridge pile settlement, the settlement proportion of each stage, the distribution of soft strata in the tunnel body, and the impact of sleeve valve pipe driving method on the bridge pile settlement were analyzed. The conclusion shows that when shield tunneling side through bridge piles in soft strata, the vertical displacement of the bridge pile shows the change rule of “first rising slightly, then sinking”; the settlement of bridge piles mainly occurs during and one week after the shield passes, accounting for 80%～90% of the total settlement; when the plane clear distance between the tunnel and the bridge pile is less than 2D, the bridge pile adjacent to the tunnel shall be pre-grouted with sleeve valve pipe around the pile for reinforcement, which can effectively reduce the impact of shield construction on the settlement of the bridge pile; the higher the distribution proportion of soft soil layer in the tunnel body, the greater the settlement of bridge piles; the sleeve valve pipe grouting hole around the pile shall be set vertically to avoid the blind area of grouting, so as to ensure the effect of soil reinforcement and bridge pile settlement control.