Deformation Characteristics of Shield Tunnel with Staggered Joints Under Bilateral Unloading Condition

Abstract:

Based on the engineering background of the Xiamen Metro Line 2 tunnel, the similar model test and the finite element numerical simulation were used. Aiming at the shield tunnel’s unloading conditions on both sides, the transverse deformation characteristics, failure modes and segment damage process of tunnel were analyzed, and the stress mechanism and the key performance points of shield tunnel under unloading condition were obtained. The results show that: the convergent deformation value of segment concrete crack width 0.15 mm of design allowable value is 3.29‰D (D is the diameter of the tunnel); the vertical section of bolt failing to yield is 10.67‰D, the structural failure form is caused by segment cracking, bolt yielding to excessive deformation and collapse.