The Ivoz-Ramet lock complex on the River Meuse near Liège lies on the Rhine/Meuse-Main-Danube trans-European priority corridor, connecting the North Sea with the Black Sea. The largest tonnage in the entire Walloon Region passes through this hydraulic lock.

In the last 20 years, the traffic at this location has grown from 6 million to 12 million tons per year. As a result, the existing 136 m x 16 m lock (class Va) is now near saturation. To allow the passage of class VIb vessels up to 9000 tons and to reduce waiting times, the Service Public de Wallonie (SPW) has, therefore, decided to build a new and larger lock, sized 225 m × 25 m, with a maximum water head of 4.45 m.

Cofferdam wall

The designers solved this problem with a cofferdam wall of 20 diaphragm cells with straight web sheet piles. The wall is auto-stable and serves as a permanent retaining wall for the island between the current and the new lock. Three arc cells were added on the side of the cofferdam wall and filled with concrete to serve as an abutment for a swivel bridge that connects the island with the right river bank.

The sheet piles were driven through the bottom of the river until the bedrock with a PTC 34 vibrator. Two single-level driving templates, resting on temporary steel tubular piles, were used to install the sheet piles: one for the 18 diaphragm cells and one for the two circular closing cells. The 20 cells of the diaphragm wall were backfilled with granular soils, and covered by a concrete slab in which vertical tie rods were installed to anchor the cells to the bedrock. Due to the high tensile forces in the interlocks of straight web sheet piles, the diaphragm cells are permanently watertight.

Downstream the lock complex, steel tubes Ø1067×11 mm were used as foundation piles for the exit guiding walls and Ø1067×14 mm for the construction of 13 dolphins. The foundation piles and dolphin tubes were installed into holes 1,500 mm and bored into the bedrock through temporary steel casings. To anchor the tubes, their base was filled with concrete, which could flow into the holes via openings in the tube’s base.

The works started in May 2011 and will be completed in 2015.