Tunnelling beneath the city centre of Toulon. The tunnel runs parallel to the north bore, in the direction of Nice/Marseille, which was already completed in 2002.
The tunnel is at the present time the most important tunnel construction project in France, and the technical challenges are enormous. Length: 3310 m, diameter: 8.25 m, depth: 35 m. The tunnel was driven from two faces, with breakthrough taking place in March 2011.
Bouygues Travaux Public Group
The site is located at a depth of 35 m, in the ground water, and has the effect of a huge drain pipe. All the construction sections must be kept dry, and the water also has to be pumped out which enters in fluctuating quantities as the tunnel is driven forwards.
Use of pumps of the KTZ Series, with components made of cast chrome iron, in order to pump the water out of the filters into the settling basins. In the settling basins there are agitator pumps of the KRS-series equippied with slow running 4-pole motors (1500 r.p.m.). Control is provided via switchboxes. High-pressure pumps of the LH Series are used to pump the water out of the settling basins. The high pressure of these pumps prevents the pipes from clogging.