Pile Capacity Setup in Fine Grained Glacial Deposits at the South Brooklyn Marine Terminal

摘要

In June of 2009 the design and construction of a materials recycling facility (MRF) owned by the City of New York and to be built and operated by Sims Municipal Recycling of New York (SIMS) at the 30th Street Pier of the South Brooklyn Marine Terminal (SBMT) was undertaken. The new facility was to be constructed on the approximately 11-acre (4.5 ha) site as part of the SBMT renovations undertaken by the NYC Economic Development Corporation. A new 850 ft long (259.1 m) bulkhead and docking facility was constructed along the southern perimeter of the pier to facilitate the reception of barges. A wharf with an enclosed over-water shed structure was also constructed in addition to other upland structures. The site was underlain by, in descending order: Fill, Organic Silt, Sand, Glacial Lake deposit (sand/silt/clay), and Glacial Till. Bedrock was not encountered within the upper 175 ft (53.3 m). Foundations for the new structures consisted of open-end steel "friction" piles founded in the underlying Glacial Lake Stratum. The required pile resistance varied by structure from 272 kips (1209.9 kN) to 460 kips (2046.2 kN). The selected pile section consisted of 24 in (610 mm) diameter steel pipes with 1/2 in (13 mm) wall thickness. The marine pile testing and installation program was challenged by large "freeze" factors in the clay and silt and a fish breeding moratorium on in-water work. Pile Driving Analyzer (PDA) testing and Case Pile Wave Analysis Program (CAPWAP) were used extensively during initial drive of piles to the anticipated tip elevation. The results of this analysis and observed pile resistances during driving indicated in-place capacities less than predicted due to development of excess pore water pressure and soil remolding. Driven piles were restruck at varying setup times (up to 4 months) to determine the rate and percentage of capacity development. An extensive PDA restrike program found significant pile capacity increase with setup time. The ultimate capacities were verified through static load testing. This paper presents the measured affects of setup time.