Prague Subway – Refurbishment and Maintenance of Older Lines

摘要

The first line of Prague’s subway system, the Metro, was inaugurated 30 years ago. Today, the PraguernMetro is operating a network of routes exceeding 50km. The alignment of the lines lies largelyrnbeneath the ground water table, often within the Vltava River’s flood-plain terrace. It passes under thernriver three times. This fact, combined with the fact that the initial tunnelling technique was based onrnthe ring method adopted from the Moscow Metro construction, which was not capable of securingrnwaterproof tunnels, causes the current huge demand for maintenance and refurbishment work. Withoutrnelastic filling, the joints between the reinforced concrete or cast iron segments are sources ofrnsignificant leakage. The leaks have had to be removed using polyurethane resins. Long-term sealing ofrnthe leaking joints, guaranteeing permanentelasticity and bond to substrate, has been achieved by arncombination of injection materials and compounds. Our paper contains experience gained from thernremedial operations, their results, and our recommendations.