Reducing the urban environment impact of joint leakage of underground prefabricated structures: Waterproof performance improvement of WSR-EPDM gasket

Abstract

Composite cross-section gaskets with ethylene propylene diene monomer (EPDM) and water swelling rubber (WSR) have been adopted for specific underground prefabricated structures to prevent water leakage. Research on the sealant behavior and waterproof failure mechanism of WSR-EPDM gaskets needs to be strengthened, and this paper presents a combined experimental and computational study to investigate the leakage behavior of WSR-EPDM gaskets. The mechanical performance of the WSR-EPDM gasket based on the 3-stages load-deformation relationship was detected using the electronic universal testing machine. And the waterproof performance of the WSR-EPDM gasket was tested based on the developed waterproof capacity test setup to monitor the water leakage pressure of joints under various combinations of joint openings and offsets. Three groups of mechanical tests and 12 groups of waterproof tests were carried out. Then, a series of finite element models were developed using the coupled Eulerian-Lagrangian method to reveal the failure mechanism of the WSR-EPDM gasket. The hyperelastic behavior of the WSR-EPDM gaskets was described using the two-coefficient Mooney-Rivlin hyperelastic model and verified against the gasket-in-groove mechanical test results. A supplementary parametric study investigated the effect of joint opening and offset. The correlation between gasket contact stress and supplied water pressure was analyzed. Finally, an improved gasket was developed, and the mechanical and waterproofing behavior was evaluated. The results indicated that the joint opening and offset negatively influenced the gasket waterproof behavior. The water-leakage path of the WSR-EPDM gasket was more likely to happen via the gasket-groove interface when the joint offset was larger. Furthermore, the mean contact pressure ratio to the water leakage pressure of 1:1 can be used as the criteria for a preliminary estimate of the potential water leakage path. The improved WSR-EPDM gasket showed excellent waterproof performance, with a maximum increasing ratio of 127.6%. The developed test setup and numerical methodology provide novel insights into the waterproof performance improvement of composite cross-section gaskets in complex situations.