The 18th caisson, the C0 is now in position.
Its function is to protect the entrance to the port and limit agitation inside. At the beginning of the project it did not exist. The possibility of building a seawall had been mentioned. But a seawall, as could be designed by a port engineer, is a maritime structure that is functional but does not fit into the aesthetic criteria. Landscape designers and architects therefore proposed to transform this seawall, which is structurally similar to a caisson, into a pool. As it is a question of maintaining proximity to the sea, this pool of unique design in terms of offshore structure and equipped with bay windows overlooking the sea was positioned extremely low. To date, there is no reference to an offshore structure of this nature.
On the one hand, we have a structure with PMMA3 ‘windows’ (PMMA3 is a translucent material, similar to glass) subjected to waves of the magnitude described in the studies,
on the other hand, waves that can overtop the caisson. Here, overtopping is no longer a concern (see in this section our series on hydraulic studies, août2019). There are no residential buildings around this caisson, nor any pedestrian traffic to worry about in case of a storm. But, as a result, we are confronted with a new type of impact: that of the waves falling back into the pool from a height of 7 to 8 metres. It’s extremely violent. The pool is only 2 meters deep. This is not enough to attenuate the shock waves that propagate. The impacts from the sea are well known. Those coming from inside a swimming pool are new. This excessive pressure must be taken into account when designing the windows. It is so specific that it has led to presentations at specialized conferences.