Bridge Responses Induced by Adjacent Subway Station Construction Using Shallow Tunneling Method

Jie Su,Qian Fang,Yunming Jie,Dingli Zhang,Xiaokai Niu,Xiang Liu

doi:10.1155/2018/8918749

Abstract

This paper presents a case of subway station construction under an existing prestressed concrete bridge with a three-span continuous beam located at the intersection of the 3rd Ring Road, Beijing. The Huayuan Subway Station of line 6, constructed crossing between #7 and the #8 piers of the bridge by the shallow tunneling method, is approximately perpendicular to the existing Huayuan Bridge. The minimum horizontal distance between the pile foundation and the subway station is only 0.08 m. The “Pile-Beam-Arc” construction sequence was used to ensure the safety of both the subway station and the bridge. Moreover, a series of reinforcement measures were adopted to safeguard the project, including deep grouting reinforcement surrounding the pile foundation from ground surface, temporary inverted arch in the middle of No. 5 drift, and the lateral steel support. Even though some cracks were observed on the bridge deck surface by the on-site deformation monitoring, the results were still within the proposed control standard. To prevent the further development of the cracks, jacking protection measure and bonded steel constructed under the box girder were performed. The related measures proposed in this research can provide useful references for future similar projects.

Highlights

With the development of public transportation in congested urban areas, more subway stations and tunnels are constructed adjacent to existing infrastructures
The active jacking was used as emergency plan to protect the bridge safety for the first time in this project. This project of subway station construction crossing to existing bridge in urban are successful and representative. e safety control schemes as used in this case are widely used in similar projects in China and have been viewed as an effective solution to protect the safety of existing structures during tunnel construction
Monitoring Results of Bridge. e monitoring results (Figures 12 and 13) show that the deformation of the existing bridge did not exceed the control standard, when the drifts far away from #8 pier were excavated completely before the subway station entered into the existing bridge area. e maximum settlement was −0.97 mm at S8-1 pier. e maximum horizontal displacement was 0.6 mm. e maximum tilt was 0.37‰. e monitoring results were under the local standard value

Summary

Introduction

With the development of public transportation in congested urban areas, more subway stations and tunnels are constructed adjacent to existing infrastructures. Several existing structures crossed by tunneling were researched, including buildings, bridges, and pipelines, Advances in Civil Engineering. E shield method or small cross-sectional excavation was used mostly in previous researches to document the response and control on tunnel excavation adjacent to existing structures. Is paper investigated the response and safety control schemes of an existing bridge due to nearby subway station construction. The active jacking was used as emergency plan to protect the bridge safety for the first time in this project This project of subway station construction crossing to existing bridge in urban are successful and representative. E safety control schemes as used in this case are widely used in similar projects in China and have been viewed as an effective solution to protect the safety of existing structures during tunnel construction.

Project Overview

On-Site Monitoring

Jacking Measures