VSF has installed two diaphragm wall barriers next to Strandweg in Scheveningen in phases for the main contractor 'Combinatie Zeefront' and the client, the Municipality of The Hague.
The diaphragm walls were used at the beginning and end of the new sea defence. This sea defence is now no longer visible, as it has disappeared under the new boulevard.
The first phase entailed a wall of around 85 metres in length and 23 metres in depth. The thickness of the wall is 1.2 metres. The wall was unanchored and, during the construction phase, had to endure one-sided excavation of 11 metres. Due to the high rise building near parts of the wall, it was necessary to work with a higher safety factor for the trench stability, single panels rather than three-way panels were used.
Due to the buildings and monuments close to the wall, in the second phase all panels were executed as single panels. Main contractor Combinatie Zeefront then started to construct a connection to the new sea defence at the site of the diaphragm wall. The soil on one side of the unanchored diaphragm wall was therefore excavated to depth of 11 metres. After completing the connection, everything was back-filled and nothing more can be seen of the work.
For further explanation of diaphragm walls, click on the following link: Excavating diaphragm walls
The diaphragm walls were excavated using a crawler crane type Sennebogen 6100. Due to the highly restricted room for excavation, to restrain the grab when unloading and placing in the trench, a hydraulic rotating Kelly system was mounted. The same type of crane was used for installing the reinforcement, using a longer boom.
On the photos, you can see how the end stops were placed. The desanding plant is placed on an excavated panel to clean up the trench and prepare it for installation of the reinforcement and the concrete. A nice contrast with the beach and Scheveningen pier in the background on a lovely spring day.