Within the framework of the 'Dyke reinforcement Nederlek' project, in cooperation with Van den Herik and Boskalis, VSF executed the anchoring of the sheet piles with screw injection anchors. Due to the existing buildings, part of the dyke in the heart of Lekkerkerk could not be reinforced this way. The two sections of 100 and 200 metres that connect to the existing flood barrier in the Voorstraat were therefore executed with diaphragm walls with a thickness of one metre and a depth of 23 metres and 24 metres respectively.
The existing buildings are founded on steel and, with restricted room to work, the majority of the diaphragm wall was executed in single panels with a width of approximately 2.8 metres. As excavator, a Sennebogen 6100 with a slurry wall grab fitted with a telescopic guide was used.
The room available was so limited that it was necessary to work almost to the millimetre to be able to place the equipment.
In a couple of places, the trench was even excavated 1 meter from the facade without causing any damage.
The soil that came from the trench was discharged into a soil container and, from there, disposed of immediately.
The reinforcement was delivered as a complete cage and unloaded and hung in the trench with the crawler crane (Hitachi 180). Concrete for the diaphragm wall was poured partly with the concrete pump for the main part directly from the mixer. The top part of the diaphragm wall was integrated in a concrete beam, which was situated partly below ground level, but largely in view.
Complex work, logistically, in view of the accessibility and working room, whereby it was also necessary to ensure that local residents experienced as little nuisance as possible and retained access to their homes.