Manulife Financial Corporate Headquarters
Manulife Financial U.S. Headquarters, completed in 2004, is located at 601 Congress Street in South Boston’s Seaport district. The soil profile for the Seaport district as described in the journal, A City Upon a Hill: The Geology of the City of Boston, can be generally characterized by 20-30 ft of fill over organic soil which sits upon 40-80 ft of outwash sand that overlays over-consolidated marine clay. All of this then sits upon lower outwash, till, and deep lying argillite. It is evident that both the high water content of the marine clay as well as the high ground water table at this site were considered given the sophistication of the split-foundation system implemented by the designing engineers. The system consisted of a 4-5 ft thick concrete mat accounting for roughly three quarters of the foundation. Such a massive mat is a result of the building covering 80 percent of it's above grade footprint. The concrete mat provides a shallow yet strong foundation capable of supporting such a large building. The rest of the building, specifically the southern portion, is supported by 4 ft diameter shafts that are drilled into the deep lying argillite that has an allowable bearing pressure of 8-10 tons per square foot (tsf). The foundation system is enclosed by a slurry wall that is toed into the marine clay as an additional measure to account for the high groundwater table considering the site's proximity to the ocean.
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