Samenvatting

This study evaluated the feasibility of a buoyant V-block closure joint for application within the Fraser River Tunnel Project and compared its performance against alternative closure joint concepts. The results demonstrate that the buoyant V-block is a technically feasible closure joint solution under the boundary conditions of the FRTP. The concept satisfies the principal requirements associated with buoyancy control, floating stability, immersed stability, ballast operations, hydraulic coupling, gasket compression, and construction-phase functionality. The analyses showed that sufficient buoyancy can be achieved to enable floating transport and controlled immersion while maintaining acceptable stability throughout all investigated construction stages. Furthermore, the hydraulic coupling assessment demonstrated that the required Gina gasket compression can be achieved through the combined effects of hydrostatic loading and dewatering operations, allowing the required watertightness performance to be obtained. The study identified several governing parameters that strongly influence the feasibility of the concept. These include water depth during coupling operations, hydrostatic pressures acting beneath the V-block overhangs, gasket compression requirements, installation tolerances, and long-term load transfer mechanisms. The interaction between these parameters proved to be one of the most important findings of the research. The tolerance assessment demonstrated that the inclined geometry of the V-block creates a direct relationship between longitudinal displacement and vertical settlement. Consequently, successful implementation requires careful coordination of closure joint geometry, tunnel element spacing and installation tolerances. The research further showed that long-term performance of the closure joint requires implementation of a secondary load-transfer mechanism such as a shear key or shoe stopper system. These components are necessary to maintain the final position of the V-block after gasket relaxation occurs and to ensure long-term stability of the closure joint assembly. The comparative evaluation of the investigated variants demonstrated that the buoyant V-block achieves the most favorable balance between constructability, operational functionality, hydraulic coupling performance, and compatibility with the FRTP project conditions. Therefore, it can be concluded that the buoyant V-block closure joint represents a feasible and competitive closure joint solution for the Fraser River Tunnel Project and merits further development during subsequent design phases.