The design and application of a large-scale model test for a super-long immersed tunnel

In this paper, based on the immersed tunnel construction of the Hong Kong-Zhuhai-Macao bridge project, the mechanism of super-long immersed tunnel segment joints under actions of uneven settlement and uneven loads is researched by means of partial similarly assembling shear keys. The large-scale immersed tunnel segment model test with a ratio of 1:4.69 is carried out by material proportioning and model fabricating, and the trial platform of the settlement model is technically transformed to possess such functions as model hauling, connecting, loading, and resetting in the process of the experiment. Uneven displacement in longitudinal and transversal directions of the immersed tunnel segment joints can be simulated through control of differential settlement of the jacks at the bottom of the trial platform. With reinforcement meters and pressure cells, the reinforcement stress of the immersed structure and the contact pressure between the model structure and the soil mass are tested, and by utilizing a resistance strain rosette and an FBG strain rosette, the external and internal strains of the shear keys are also tested. Furthermore, the distribution laws of segment joint shearing stresses along with differential settlement and immersed tunnel cross sections are obtained by a preliminary analysis of the test data. ©, 2014, Editorial Office of Modern Tunnelling Technology. All right reserved.