Waterproof performance and failure mechanism of GINA gasket subject to diverse joint deformations: A case study of the Yuliangzhou immersed tunnel

GINA gasket serving as the primary sealing unit of the element joint, directly influences the waterproof performance and longevity of the immersed tunnel. The Yuliangzhou immersed tunnel in China was taken as the research background. Compression deformation tests and corresponding numerical simulations were adopted to study the contact stress distribution and limit deformation of GINA gasket under diverse joint deformation conditions. In addition, failure process, failure mode and relationship between contact stress and failure water pressure were investigated by the coupled Euler-Lagrange model (CEL). The results demonstrate that irrespective of the deformation condition, the top contact stress on the GINA gasket significantly exceeds that on the bottom. This disparity identifies the bottom as the predominant leakage pathway. The joint opening significantly affects the waterproof performance of the GINA gasket, with the limit opening 47 mm. Offset deformation has minimal influence on the waterproof performance of the GINA gasket, and in some cases, appropriate offset can enhance waterproof performance. Joint rotation angle primarily impacts the amount of opening in the GINA gasket, which subsequently affects contact stress. The limit rotation angle is 0.41°. When joint offset and rotation occur simultaneously, joint offset will weaken the influence of rotation on the bottom contact stress, which is good for the maintenance of waterproof capacity. Under combined deformation conditions, the limit rotation angle is 0.51° when the offset is 60 mm. The waterproof failure process of the GINA gasket can be divided into four stages: joint deformation stage, water extrusion stage, water breakthrough stage, and waterproof failure stage. In opening and offset conditions, GINA gasket's waterproof failure occurs due to its overturning, which reduces contact stress on the bottom. Under rotation angle conditions, the failure is attributed to significant deformation that also leads to insufficient contact stress on the bottom, ultimately causing the leakage. During the failure process, the water pressure follows the same variation pattern as the contact stress, indicating that the waterproof performance of the GINA gasket can be assessed by studying its contact stress. • The mechanical behavior of GINA gasket under diverse joint deformations is studied. • Bottom is the main leakage pathway of GINA gasket. • The limit deformation is determined based on the relationship of average contact stress and waterproof index. • CEL waterproof failure model is used to investigate the failure mechanism of GINA gasket. • The failure process, mode and relationship between contact stress and failure water pressure are studied.