It is described how, faced with a demand to 'buy American,' engineers designed a better segmental lining for sections of the Washington, D.C. subway. The 4-mile, single-pass, bolted and gasketed segmented concrete lining marks a new state of the art in U.S. tunneling technology. It provides circular tunnels 16 ft 8 in. i.d. and 18 ft 4 in. o.d. Seven segments, including a key, combine to form one 4 ft wide coffered tunnel lining ring. Construction is advanced ring by ring behind a tunnel boring machine. The systems advantages are described and include the following: eliminates the need for temporary tunnel support; and bolted design ensures safety during construction in non-uniform or water bearing ground. The segments are designed to withstand handling, erection, earth loads and water pressure. Details of production and logistics are summarized. Directions for future research are indicated.

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Filing Info

  • Accession Number: 00488920
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 31 1989 12:00AM