Construction Influence Analysis and Control Measures of Shield Tunnel Side-crossing Adjacent Bridge Foundation

During the construction of the interval tunnel from Tianqiao station to Yongdingmen Wai station of Beijing Metro Line 8, the shield machine has to cross the West Yongdingmen Bridge in close distance at the mileage from K34+422.094 to K34+534.308. The stratum at the crossing section is mainly sandy cobble soil. The minimum net distance between the bridge and the shield tunnel is only 9.2 m when the shield arrives at the mileage of K34+506.308, of which the construction has relatively large impact on the bridge structure. Therefore, it is necessary to evaluate the safety of the bridge structure caused by shield construction. According to the dynamic simulation analysis of the construction process of shield machine sidecrossing bridge foundation, conclusion is obtained that the deformation of the stratum and the bridge structure caused by shield tunnel sidecrossing construction is too large. In view of this, a local grouting scheme to reinforce the soil around the left tunnel near the bridge and control measures for the management of shield tunneling parameters are proposed. Both calculation analysis and field monitoring results show that the deformation of the stratum and bridge structure can be effectively controlled if the above engineering measures are taken, thus smooth construction of this project is ensured, providing reference for similar projects in the future.