A fluid-solid coupled modeling on water seepage through gasketed joint of segmented tunnels

Abstract

The water leakage at segment joints of underwater shield tunnels has always been the major concern and trouble to be dealt with in tunneling practices, not only for its threat to the durability and safe operation of tunnels but also for its difficulty to check the leaking process directly in the joints either on-site or in the laboratory test. In order to explore the water leakage mechanism of the segmented tunnel, a Coupled Eulerian-Lagrangian based model considering water flow and large deformation of rubber gasket was developed to simulate the whole process of water seepage through the gasketed joint. A series of numerical modelings were conducted to investigate the seepage pattern and the stress variation during the seepage process, and the dynamic waterproof performance of gasket was investigated. Then, the numerical modeling results were verified against the laboratory test data to prove the reliability of the proposed numerical method. Finally, a formula quantifying the relationship between the waterproof capacity and joint deformations was established, and the critical joint deformation sets were derived from the formula. It was found that the water has an impact effect on the gasket during seepage, which is up to 4 times the initial contact stress. The pressurized water must overcome a cluster of seepage stress barriers to form a seepage path through the gasketed joint. And therefore, the waterproof performance over the length of the gasket-gasket interface is changing and fluctuating with the seepage process, with higher values at both ends of the interface and lower values in the middle. Based on a comprehensive analysis, the critical joint deformation sets (joint opening, joint offset) are recommended for the design and construction of Qiongzhou Strait Tunnel (a planned deep-water shield tunnel in Hainan Province, China) to meet the long-term waterproof capacity of 2 MPa. It is suggested that the assembly accuracy of the segments and gaskets as well as the adhesion of gaskets to joint groove should be strongly guaranteed during the construction process.