During the construction of a suspension bridge over a sea inlet, the civil engineering company had to find a system capable of :
• compensating height differences between bridge and sea bottom, (about 35 to 80 cm)
• resisting to up to 20 cm high sharp bottom roughness.
• supporting the weight of the frame (measuring 52 x18 x 26 meters and weighing 2000 tons).
We have manufactured trapezoïdal grout bags made in high tenacity fabric, with two layers to avoid punching problems.
The performed tests under 400 ton pressure and on a range of 20 cm spines have proved a totally satisfactory. These grout bags are provided with two outlets and one grouting inlet. Internal bands avoid adhesion of the grout bag during grouting.
These grout bags are first placed into a rigid frame, where they are maintained with restraining straps. The resistance to elongation of the straps has been calculated so that the bag remains in its frame until the main concrete frame is placed info the water. This system allows the grout bag to develop correctly during its filling without showing any crawler effect