Mécanique des vases appliquée à la stabilité des ouvrages : réalisation de digues et d'ouvrages d'art à bouin et à l'aiguillon

The consideration of mechanical mud properties in seeking to achieve stuctural stability Dyking and other works at Bouin and l'Aiguillon

Président-Directeur Général de CO-TRA-MAT.

Résumé

The protection of coastal marshland requires dykes along the sea shore and enclosing the vulnerable area. In addition to the problems associated with the purpose of such works, their construction also involves others connected with their own safety against the sea, among which especially the stability of very long dykes. For example :- (i) Such structures are built on layers of heterogeneous thixotropic very highly compressible materials; (ii) In order to keep costs down the dyke materials are if at a possible obtained from a borrow in the immediate vicinity of the structure; (iii) Both the ground thedyke stands on and the dyke core material are regularly exposed to waves and gales during construction; (iv) Once the stahility and sealing of the dyke are ensured the necessary drains must be provided for throught the structure. All these problems and requirements arose during construction of the following:- a) Ocean dykes at Bouin below high water neap tide level (between 2 m and 9 m a.d.) totalling 7 km in length. b) Mud dykes at l'Aiguillon at the high water neap tide limit (4.15 m to 8 m a.d.) with outlets through them for flows varying from 20 cu.m/sec. to 80 cu.m/sec. and a total dyke length of 8 km. One of the conclusions drawn from this experience was an apparently most effective method of determining the right structural cross-sections for given foundation systems and working methods.