Aging Test System and Its Application for GINA Gaskets of Immersed Tunnels under Compression Load and Seawater Environment

GINA gaskets are installed between adjacent elements of immersed tunnels to prevent external seawater from entering the tunnel, playing an important role in waterproofing. An aging test system of gaskets considering compression load and seawater environment was designed and applied. Subsequently, the deterioration characteristics, including the elastic property, Shore A hardness, density, and contact stress, were evaluated under various aging times and temperatures. Finally, the service life was assessed by the time–temperature superposition principle. The results revealed that, after a 90-day aging period, the tensile strength and 200% tensile stress decreased by 14.43 and 0.75 MPa, respectively. Meanwhile, the Shore A hardness and density increased by 14.18% and 5.88%, and the contact stress decreased by 67.66%. These changes become more pronounced with increasing aging temperature. After 100 years, the contact stress of gaskets remained above the waterproofing index, thus meeting the design service life of immersed tunnels without considering other factors such as joint deformation.