JUL 2018


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JULY 2018 52 CompositesWorld FOCUS ON DESIGN Composites perform water rescue in high-speed transport tunnel Channeling out the great quantities of water that flow into Spain's Pajares railway tunnels in the Cantabria Mountain range required an award-winning composites innovation. » When it comes to water intrusion into transit tunnels, there's seepage, and then there are the Pajares Tunnels in Spain. Part of a future high-speed rail line intended to link centrally located Madrid to the Principality of Asturias, a region on the country's northern shoreline known for its rugged coast and mountains, the 24.6-km twin tunnels will enable high-speed rail service through the Cantabria Mountains. Until now, the only rail passage through the mountain range was a winding, sometimes steep route, used primarily for freight, that limited train speeds to 70 km/hr. e new route will provide passenger travel at speeds topping 300 km/hr. e twin tunnels are among the longest in the world, but they have proven to be among the most challenging to engineer. One reason? e Cantabrian region is known for its lush vegetation, enabled by a very wet climate. Positioned on the Bay of Biscay, with wet Atlantic winds trapped by its mountain range, it reportedly can tally up to 1,200 mm of annual precipitation! Initial tunnel construction was completed in 2009, but unprec- edented water infiltration threatened to thwart rail line installa- tion. Water was seeping in from the surrounding soils at a rate a full order of magnitude greater than is seen in most tunnels — up to 2,200 liters/sec, enough to fill an Olympic-sized swimming pool every 20 minutes. e culprits were cracks in the tunnels' concrete walls. Conventional approaches to waterproofing — injecting poly- meric paste into the cracks, installing a polymeric membrane — and other attempts to seal tunnel walls or retrofit tunnels with an existing abatement solution proved ineffective. A new solution was needed, and Madrid, Spain-based ACCIONA Infraestructuras S.A. – Technology & Innovation Div. was tapped Composites offer creative seepage solution This composite lining, designed to channel large volumes of concrete-wall water seepage down to canals that transport the water out of this tunnel and away from its railway, also makes a striking visual impression in one of northern Spain's Pajares Tunnels. Source | ACCIONA By Karen Mason / Contributing Writer

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