Failure mechanism of joint waterproofing in precast segmental tunnel linings

Abstract

Water leakage is a major issue for shield tunnels in both the construction and operational stages. The practical solution in industry with relation to the prevention of groundwater penetration is to implement ethylene-propylene-diene monomer (EPDM) gaskets at tunnel joints. Although a few past research has focused on joint waterproof performance, this paper proposes a sealant mechanism based on the finite element analysis. A conceptual model is first established to identify sealant behavior of gasketed joint subjected to lateral water pressurization. A nonlinear finite element model is developed to simulate the gasket-in-groove sealant behavior, and the performance of the model is validated with experimental data. Results of the nonlinear numerical analyses (incorporating a hyperelastic constitutive model of the gasket, complex contact properties, and large deformation) demonstrate the failure mechanism of joint waterproofing. Emphasis is placed on quantifying the effects of joint opening, joint offset and joint rotation on waterproof capacity. The computed results indicate that joint waterproofing capacity significantly decreases with increasing joint opening or joint rotation. The waterproofing capacity varies under different joint offset scenarios because of change of contact interfaces. For the prototype tunnel, it is suggested to control a 6.42 mm joint opening, a 0.0505 rad positive joint rotation or a 0.0141 rad negative joint rotation to maintain its waterproofness.