Construction Plan and Risk Analysis of New Subway Tunnel Passing Beneath Existing Subway Station and Slurry Walls

Metro lines need to be interconnected with each other to form a network. During networking, tunneling beneath existing tunnels, stations and, possibly, through the slurry walls used as the support of station excavation, occurs frequently. Tunneling closely beneath existing structures and through slurry walls create significant risks. This paper deals with the construction plan and risk analysis of Suzhou Metro Line No. 8 tunneling beneath Suzhou Metro Line No. 1 Huachi Station and the slurry walls. The paper summarizes the existing construction techniques for tunneling beneath existing structures and through slurry walls based on four case history projects. A risk analysis is performed on different alternative construction plans and the final construction plan is recommended for the Suzhou project. Three-dimensional numerical analysis is performed on the recommended plan and proves that the impact of the tunneling on the existing subway station is minimum.