英法海底（隧道英文）.doc

Channel Tunnel (French: Le tunnel sous la Manche， 英法海底隧道）The Channel Tunnel (French: Le tunnel sous la Manche), also known by the portmanteau Chunnel[1], is a 50.5-kilometre (31.4 mi) undersea rail tunnel linking Folkestone, Kent in England with Coquelles near Calais in northern France beneath the English Channel at the Strait of Dover. At its lowest point it is 75 m (250 ft) deep.[2] The Channel Tunnel has the longest undersea portion of any tunnel in the world, but the Seikan Tunnel in Japan is both longer and deeper overall, at 53.85 kilometres (33.5 mi) and 240 metres (790 ft) respectively. The tunnel carries high-speed Eurostar passenger trains, Eurotunnel ro-ro vehicle transport and international rail freight trains. In 1996 the American Society of Civil Engineers identified the tunnel as one of the Seven Wonders of the Modern World. Surveying undertaken in the 20 years before tunnel construction confirmed earlier speculations that a tunnel route could be bored through a chalk marl stratum. The chalk marl was conducive to tunnelling, with impermeability, ease of excavation and strength. While on the English side the chalk marl ran along the entire length of the tunnel, on the French side a length of 5 kilometres (3 mi) had variable and difficult geology. The Channel Tunnel consists of three bores: two 7.6-metre (25 ft) diameter rail tunnels, 30 metres (98 ft) apart, 50 kilometres (31 mi) in length with a 4.8-metre (16 ft) diameter service tunnel in between. There are also cross-passages and piston relief ducts. The service tunnel was used as a pilot tunnel, boring ahead of the main tunnels to determine the conditions. English access was provided at Shakespeare Cliff, while French access came from a shaft at Sangatte. The French side used five tunnel boring machines (TBMs), the English side used six. The service tunnel uses Service Tunnel Transport System (STTS) and Light Service Tunnel Vehicles (LADOGS). Fire safety was a critical design issue. Between the por