It is a project of enormous size and expense, but it will ultimately link two countries via a high-speed rail line. Both tourists and freight will travel at speeds up to 186 mph as they ride between Perpignan, France and Barcelona, Spain.
The journey used to take almost three hours to complete, but that time will be reduced to only 50 minutes with the new Train à Grande Vitesse (TGV).
Le Perthus tunnel is the link between Perpignan in France and Figueras in Spain in the French/Spanish border town of Perthus. Two 28½-ft-diam. tunnels, each 5.2 miles long, is part of the overall link connecting the two countries.
The work on the French side of the railway was completed by the contractor group EIFFAGE Travaux Publics, France, based out of Lyon, France. Part of their responsibilities included slipforming the concrete base slab on which the railway for the high-speed track would be laid, and the two side platforms.
This is the first tunnel project for the company. They needed to slipform five different profiles inside the tunnel’s limited space. EIFFAGE chose to purchase three concrete pavers with the various mold profiles.
EIFFAGE’s first project inside the tunnels was slipforming the base slab, or tunnel floor. The floor had an average thickness of 23.6 in. and was 18.4 ft wide. Cross slope of the floor varied between zero and 7.67%. Three different drainage pipes, varying in diameter from 9.8 to 15.75 in., were incorporated into the floor during slipforming.
On track
The four-tracked concrete paver had its tracks turned at 35° angles to run along the slope of the tunnel walls. The inner leg tubes were turned 45° from their normal position to accommodate the tunnel-paving application.
Concrete was supplied by an onsite batch plant on the Spanish side of the tunnel. Ten specially designed mixer trucks carried 7.8-cu-yd loads of concrete to the paving site. Two special crossing platforms were fabricated inside of the tunnel to allow the trucks to pass by each other. A turntable in front of the paver swiveled the trucks 180° so they could dump into the hopper of a custom-built concrete spreading system.
“I think the most difficult aspect wasn’t the slipforming, but delivering the concrete with trucks inside the tunnel,” Luc Riottot, Perthus Tunnel jobsite manager, said. “When we paved the floor, we paved from France towards Spain in both tunnels. The system allowed the trucks to pass each other, turn around and return back to the concrete batching plant.”
The paver, a GOMACO Commander III, was equipped with the Leica Geosystems’ stringless guidance system and the Minnich Auto Vibe vibrator monitoring system.
EIFFAGE worked continuously, 24 hours a day, seven days a week, slipforming the tunnel floor. In 11 weeks time, they finished the floors in both tunnels, slipforming 62,781 cu yd of concrete.
Side step
With the floor complete, it was time to bring in three-track concrete pavers, also Commander IIIs. Each was equipped with a high-drive track on the front leg for tight-clearance paving. The narrow track could run between the tubes and piping that had to be slipformed into the side profiles.
The first of the side profiles to be slipformed was a slotted drain with a 9.8 in. diameter. The profile was designed to drain away any dangerous liquids that could potentially spill from the goods transport trains. The slotted drain was slipformed the length of one tunnel, then the concrete paver would be moved to the adjoining tunnel and slipform the drain back in the opposite direction.
Next to the drain, a rectangular profile was slipformed over a 9.8-in.-diam. drainage pipe and four 6.3-in.-diam. tubes for electrical cables. The profile was 19.5 in. thick and 4.8 ft at its widest point.
With both profiles complete, it was time to begin work on the profiles for the opposite sidewall.
“We used two passes and two molds, because the complete profile was more than 1.3 cu yd of concrete and we thought that was too much to slipform in one pass,” Frederic Gratessolle, manager of EIFFAGE’s Large Concreting Pavement Division, said. “The first layer was a rectangular profile. On top of that, we slipformed a double-U-channel profile. The channels will hold pressure-water pipe for fire protection, and a tube inside the concrete will house more electrical cables.”
The surface of the profile also will serve as a passenger walkway in case of emergency exits.
Trucks carrying concrete for the profiles would enter the tunnels from France, drive up on a ramp so they could get by the paver, unload onto the machine’s high-volume auger conveyor and then exit the tunnel toward Spain.
“One of the difficulties of the project was the difference between the theoretical position of the tunnel and its real position,” Riottot said. “Sometimes we would have to manage up to 9.8-in. differences. To resolve the issue, we used telescoping molds.”
By the time Le Perthus tunnel project was completed, EIFFAGE had slipformed 36,622 cu yd of concrete and five different profiles, each with a length of 10.4 miles, for a grand total of 52.2 miles.
