JUL 2018


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53 Rail Tunnel Seepage Solution Illustration / Karl Reque ACCIONA Composite Panels for Pajares Transit Tunnels › Composite laminate 4 mm thick meets physical and mechanical design requirements without compromising tunnel clearances. › Panel design allowed use of standard transportation and installation equipment, optimizing cost and time efficiencies. › Design for manufacture enabled production of 15,000 panels, each 9.2m by 1.5m, at a rate of 34 minutes per panel. for the job. "We realized we could not stop the water from coming out, so we looked for a way to channel the water," recalls ACCIO- NA's then composites manufacturing head Anurag Bansal, who now serves as the division's global business development manager. ACCIONA's innovative solution, consisting of a now- patented composite lining and anchorage system, merited a 2017 JEC Innovation Award in the construction category. Design challenges One key consideration that led to the choice of composites over other material options was the need to maintain sufficient tunnel diameter. e raw tunnel cut could have been larger, potentially allowing for a noncomposite water-channeling system, but Bansal emphasizes, "Every additional millimeter that has to be excavated is expensive." Of course, additional excavation at this point in the project was infeasible, because construction of the tunnel walls was already substantially complete. e water channeling system's thickness, therefore, could not compromise tunnel clearances. at ruled out conventional options. To meet structural require- ments, cement panels, for example, would have had to be 10 cm thick, unacceptably diminishing the tunnel's size. But the thick- ness of the laminate in the composite design is a mere 4 mm; and the panel profile, which creates water pathways in the form of integrally manufactured longitudinal ribs/channels, decreases tunnel diameter by an acceptable amount. Another key consideration was that the water-channeling system's panels would have to provide adequate radial strength once they were fastened in place against the curved tunnel walls. Panels conform to tunnel radius Water seepage channeled to concrete canals Panels sized to accommodate standard transport equipment Panels fabricated flat for manufacturing efficiency 4-mm-thick laminate maintains tunnel clearance Integrally manufactured channels direct water out of tunnel 1.5m 9.2m

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