超长沉管隧道大型模型试验设计与应用

The Design and Application of a Large-Scale Model Test for a Super-Long Immersed Tunnel

文章结合港珠澳大桥沉管隧道工程实例,采用局部相似装配式剪力键方案,对超长海底沉管隧道在不均匀沉降及不均匀荷载作用下的节段接头作用机理进行了研究。经材料配比与模型制作,进行了1:4.69的大型沉管节段模型试验;沉降模型试验平台经技术改造,能够满足试验过程中的模型搬运、对接、加载、复位等功能;控制试验平台底部千斤顶的差异沉降,可以模拟沉管节段接头纵向与横向的不均匀变位;采用钢筋计及压力盒对沉管结构钢筋应力、沉管结构与土体的接触压力进行测试,采用电阻应变花和光纤光栅应变花对剪力键表面及内部的应变进行测试。通过对所得试验数据的初步分析,得到了节段接头剪力键剪应力随差异沉降及剪应力沿沉管横截面的分布规律。

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, con-necting, 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.