Lateral Equivalent Stiffness of Large Diameter Shield Tunnel Lining Structure at Various Buried Depths

Abstract:

The overall performance of shield tunnel lining structure is affected by the discontinuities of its longitudinal and circumferential joints. The load acting on the joints varies with the variation of buried depth of lining structure. As a result, the joint stiffness and the lateral equivalent stiffness of the overall structure also vary with the variation of buried depth, especially for large diameter shield tunnels. Taking the lining structure of Shanghai Yan Jiang Tunnel as an example, the lateral stiffness of large diameter shield tunnel lining structure at different buried depth was studied based on the lateral deformation equivalent principle and the structure test results of longitudinal joint. The influences of foundation stiffness and staggered assembling on the lateral stiffness were also studied. Numerical analyses reveal that the lateral stiffness of the structure is dependent on the buried depth. For the shallow buried tunnel, the lateral effective stiffness varies greatly. When the buried depth is greater than 1.0D (D is the tunnel diameter), the lateral effective stiffness first increases and then decreases with the increase of buried depth. When the buried depth is greater than 2.0D, the lateral effective stiffness stops decreasing because of the arching effect of the ground. In addition, the lateral effective stiffness is also influenced by the ground condition. The findings of this paper can serve as a reference for the design and analysis of large diameter shield tunnel lining structures.

Key words:large diameter shield tunnel; lateral effective stiffness; beam joint model; numerical calculation