Use of cut-and-cover method to construct a 10 km long large-span underwater tunnel: case study

This paper presents a comprehensive case study of the construction of a 10 km long large-span underwater tunnel under Taihu Lake using the cut-and-cover method. The main challenges for the design and construction of the tunnel are limiting soil deformation and tunnel settlement, controlling the groundwater table, improving the construction efficiency, and meeting the environmental requirements. The strategies to address these challenges were summarized, including a four-zone staged excavation configuration, the use of piles for tunnel settlement control, and the use of cofferdams and waterproof curtains for groundwater control. The effectiveness of these strategies was validated by field observations, including deformations and stresses of cofferdams, retaining wall deflections, vertical and horizontal ground movements, groundwater table variations, and tunnel settlements. The…