The first line of Prague’s subway system, the Metro, was inaugurated 30 years ago. Today, the Prague Metro is operating a network of routes exceeding 50km. The alignment of the lines lies largely beneath the ground water table, often within the Vltava River’s flood-plain terrace. It passes under the river three times. This fact, combined with the fact that the initial tunnelling technique was based on the ring method adopted from the Moscow Metro construction, which was not capable of securing waterproof tunnels, causes the current huge demand for maintenance and refurbishment work. Without elastic filling, the joints between the reinforced concrete or cast iron segments are sources of significant leakage. The leaks have had to be removed using polyurethane resins. Long-term sealing of the leaking joints, guaranteeing permanentelasticity and bond to substrate, has been achieved by a combination of injection materials and compounds. Our paper contains experience gained from the remedial operations, their results, and our recommendations.
展开▼
