Abstract
Railway station throats have the most stringent standards for permissible deformation caused by adjacent construction. This paper describes the case of a safely implemented shield tunneling project beneath the throat of a large railway station with more than 11 tracks in soft soil areas. By identifying major design constraints, the route scheme and line alignment were established to balance the engineering conditions, which have a potential impact on the railway switches. Finite element model simulations were performed to estimate the track displacements. These simulations demonstrated the need for ground improvement. The ground improvement strategy involved the use of compact machinery to operate in the small area between the tracks. Furthermore, the earth-pressure-balanced shield machine, tunnel segments, and synchronized slurry were optimized to the site conditions. A trial section of tunnel boring was used before reaching the railway to confirm appropriate shield machine parameters. An automatic monitoring system provided continuous feedback for precise control of the construction parameters. Ultimately, the construction project achieved its goals, causing a maximum track displacement of 8.4 mm. This report also describes our experience in organizing a joint workshop consisting of the railway administration and operation teams, the metro design team, and construction, survey, and consulting companies to enhance project planning. This study provides valuable insight and can serve as an important reference for similar future projects.
Highlights
With the expanding scale of urban rail transit construction in China, existing passenger railway stations are increasingly being used as metro line stations, resulting in underground complexities, as discussed in previous reports [1,2,3]. e shield tunneling method is commonly used in metro rail construction to excavate tunnels for the railway
To facilitate efficient passenger transfer in case of large passenger volumes, it is preferable for the metro station to be close to the passenger railway station, in which case, the metro railway tunnel will inevitably cross under the turnouts located in the passenger railway station throat
The station throat is the constricted area at the end of a railway station connected by turnouts and crossing lines, and running lines divide into platform tracks at the station throat
Summary
With the expanding scale of urban rail transit construction in China, existing passenger railway stations are increasingly being used as metro line stations, resulting in underground complexities, as discussed in previous reports [1,2,3]. e shield tunneling method is commonly used in metro rail construction to excavate tunnels for the railway. The station throat is the constricted area at the end of a railway station connected by turnouts and crossing lines, and running lines divide into platform tracks at the station throat. Huo et al [1] described three shield tunneling projects conducted in Shanghai, which caused a 16.76–25.4 mm subsidence of the railway subgrade above the tunnel, even with grouting improvement In cases with such pronounced subsidence, the functionality of the railway switches is not adequately protected. Is paper presents a case study of ensuring safe implementation of shield tunneling for the construction of Shanghai Metro Line 15, which crosses beneath the turnout areas of Shanghai South Railway Station. Details are provided regarding the route scheme comparison, numerical simulation, design of the improvement range, improvement method selection, mechanical optimization, construction parameter control, and real-time monitoring feedback involved in this project, as well as the coordinated efforts of multiple project stakeholders. is article provides valuable insight into complex railway construction projects and will serve as an important reference for similar projects
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