Gina - Trelleborg Custom Designed Tunnel Seals

Gina Gasket

The Gina gasket and Omega seal are used between the sectional elements of immersed tunnels to prevent water ingress due to external water pressure. This combination of high water pressure seals not only allows for sealing but also for the transfer of the hydrostatic loads and movements between the tunnel ends due to soil settlement, creep of concrete, temperature effects and if required earthquakes

Application of the GINA gasket

An immersed tunnel is normally constructed from structural concrete elements approximately 100-150 meters long, which are manufactured in a casting basin or dry dock. The tunnel elements are provided with temporary bulkheads at both ends to ensure that the element is watertight and capable of floating. On one end of each tunnel element, an endless Gina gasket is mounted. 

When manufacturing of the tunnel elements is completed,the dock is flooded and the elements floated. Each element is towed to its final position and then immersed. The immersed tunnel element is then pulled firmly up against the preceding immersed element with hydraulic jacks. The initial contact of the large radial seals and large axial seals should be accomplished using a low pulling force. 

When the Gina Seals has full contact around the total circumference of the adjacent element, the water between the bulkheads is pumped out. Due to pressure differential between the bulkheads and the hydrostatic pressure on the outside of the tunnel, the Gina profile compresses and seals the joint. A secondary seal, the Omega seal, is then clamped across the joint on the inside of the tunnel. In general the bulkheads are removed after approval of the pressure test between the Gina and Omega.

Video

How to build an immersed tunnel

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