Manhattan Cruise Terminals Geotechnical Assessment: Analysis of Timber Piles in Soft Organic Silts-PPT Presentation

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The geotechnical assessment examined Manhattan Cruise Terminal Piers 88, 90, 92, and 94, with detailed analysis focused on Pier 88. The piers are founded in very soft organic silts and clays over bedrock, with sand layers present near some offshore areas. The study combined historical boring data, new Standard Penetration Tests, laboratory soil testing, and structural information.<br /><br />At Pier 88, approximately 2,500 timber piles support the structure. Sonic nondestructive testing of 32 piles indicated an average length of about 70 feet. However, capacity calculations suggested that an equivalent 100-foot pile was needed to meet the historical design capacity of 18 tons. The assessment therefore considered possible unrecorded pile splices or timber tip extensions, which the sonic testing may not have detected. The study concluded that sonic testing alone was not a reliable way to establish pile capacity; parallel seismic testing or full-scale axial load testing could provide better estimates.<br /><br />Analyses evaluated pile bearing capacity, axial and lateral soil response, and settlement. A single pile’s estimated allowable capacity was 18 tons, reduced to about 11.75 tons when group effects were considered. Soil-spring curves were developed for structural modeling.<br /><br />For a typical pile cluster, primary consolidation settlement was estimated at 15 inches, with about 95% consolidation expected since the pier’s construction in 1935. An estimated 13 feet of soil deposited above the original mudline may also cause negative skin friction, adding roughly 6 inches of settlement. Combined settlement was estimated at approximately 21 inches, broadly consistent with observed uniform settlement. Some areas showed excessive settlement where current loads may exceed pile design capacity, likely due to later additions, renovations, and maintenance.

Keywords

geotechnical assessment

Manhattan Cruise Terminal

Pier 88

timber piles

soft organic silts

Standard Penetration Tests

sonic nondestructive testing

pile bearing capacity

settlement analysis

negative skin friction