Structural Strength Investigation for Concrete Shield Tunnel Linings in Construction Material Strength vs. Structural Stability

Shield tunnels are widely used in the urban infrastructure facilities, and they are commonly installed through connecting the concrete or steel segments with the longitudinal and circumferential joints. In this paper, the constructing shield tunnel linings mainly subjected to the external pressure are selected to investigate its strength, as well as the effects of concrete material and multi-longitudinal joints. The findings of this study clearly indicates that, the tunnel linings fail in the structure instability rather than the material failure, and thus its structural strength is determined by the buckling strength rather than the material strength. However, the concrete elastic modulus has great impact on the structural strength by changing the structural stability. The joints affect the stability of a tunnel lining significantly; generally, the critical pressure decreases with the decreasing of the flexural rigidity and the increasing of the number of radial joints. Additionally, the arrangement of the joint location can also affect the structural strength. Keywords—Shield tunnel, concrete segment, multi-joints, structural strength, structural stability, material strength, buckling analysis