Harvard Square subway station of the Massachusetts Bay Transportation Authority has the first slurry walls ever built as a permanent part of a structure. When MBTA began to extend its Red Line 3 miles to a new terminal, it was necessary for the existing Harvard Square station to be modified and enlarged without damaging adjacent historic buildings of Harvard University. The new station, built on a curve, is as close as 7 ft to historic building foundations. A 3 ft thick slurry wall was key to excavating this tight site. While rigid slurry walls had become commonplace to protect nearby structures, none before had been built as a permanent subway element. The bentonite slurry wall also had to provide a degree of groundwater cutoff. Extensive geotechnical studies were done in 4 phases. Construction began in March 1979 and the slurry walls were completed in August 1980. An extensive field monitoring program was designed to detect ground movements, foretelling as possible danger to historic structures. As a result of thorough surface investigations during design, careful construction monitoring and good practices by the contractors, the slurry walls have performed better than expected.

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  • Accession Number: 00454898
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 31 1988 12:00AM