Spanning the Seine Estuary, the Normandy Bridge is planned to link the two cities of LE HAVRE and HONFLEUR in 1993. With a distance between pylons of 856 m, this structure holds the world record for a gantry bridge span.
The northern pylon is situated in the estuary, close to the navigable channel. Thus the designers had to ensure that it was protected against any accidental impact from vessels sailing up the Seine towards ROUEN, which can measure up to 100,000 tonnes. After studying various protection systems the engineers found an ingenious system based on straight web sheet piles.
The method of protection invothes surrounding the base of the pylon, which is the shape of an inverted Y, with a belt-type structure consisting of 13 sheet pile cells. The circular sheet pile cells have a diameter of 9 m and are 16 m high. They are connected by junction piles. The cells are made more rigid by being filled with "colcrete" type concrete, comprising gravel injected with cement grouting. The belt is externally reinforced by hard rip-rap.
The artificial island thus formed acts like a huge car bumper. The structure uses over 1,000 tonnes of straight web sheet piling.
|Owner||LE HAVRE Chamber of Commerce and Industry|
|Mains Contractors||Direction Départementale de l''Equipement de Seine-Maritime and SETRA assisted by SOGREAH|
|Sheet piles||R 500 J 9.5, 127 kg/m2|
|Interlock strength||300 t/m|
|Other profiles used||PU25: 67 t, PU8/PU6 : 12 t.|
|Steel grade||E 270 SP|