Utilizing PVDs to Provide Shear Strength to Saturated Fine-Grained Foundation Soils
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This paper describes a major case history failure of 300,000 m3 of soft foundation soil (while being surcharged) that used sand drains to shorten the consolidation time. It occurred in 1960 and has never been reported in the open literature. Using data from this case history a computer analysis is used illustrating the situation and concerns involved. With the advent of prefabricated vertical drains, the hypothetical installation of PVDs is counterpointed to this same sand drain case history showing how factors-of-safety are increased. Used are laboratory generated tensile strengths of commercial PVDs at various angles using a special apparatus developed for the first time and reported herein. The factors-of-safety against the actual case history foundation soil failure increases by approximately 4% using commercially available PVDs at typical spacings. Using stronger PVDs and/or closer spacings there is no limit as to potential increases in factors-of-safety. To the authors knowledge this is the first time that PVDs used for site drainage have been considered as reinforcement materials insofar as foundation soil stability is concerned. We hope that further advances can be made in this regard.
KeywordsPrefabricated vertical drains PVD reinforcement Soil stabilization Soil consolidation
We sincerely thank the many sponsoring organizations of the Geosynthetic Institute (GSI) for their ongoing financial support. This report is part of the ongoing publications activity at the institute. Current GSI member organizations and their contact members are available on the institute’s Web site at http://www.geosynthetic.institute-org. Board of Director members are also listed accordingly.
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