CASE HISTORY: ROCKEFELLER UNIVERSITY RIVER CAMPUS BUILDING MINI‐ CAISSONS-Paper

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Rockefeller University’s Stavros Niarchos River Campus project required a two-story building spanning the six-lane FDR Drive in Manhattan. Its foundations had to be built in confined spaces beside existing buildings, active utilities, the East River esplanade, and the highway, while maintaining traffic and pedestrian access.<br /><br />The contractor, Posillico, proposed two mini-caisson alternatives to reduce cost and shorten construction. For foundations west of the FDR Drive, 16 battered mini-caissons replaced a proposed rock-supported shear wall and rock anchors. Nested steel casings isolated load transfer below neighboring building foundations, while rock sockets carried compression and tension. The option avoided nearly 2,700 tonnes of rock excavation and associated handling.<br /><br />East of the highway, Posillico increased the diameter and capacity of many caissons from 340 mm and 5,425 kN to 457 mm and 10,850 kN. This reduced the planned pile count from 60 to 40 and was estimated to save about two weeks on a six-week critical-path activity.<br /><br />Both foundation solutions required drilling casings into bedrock and partially extracting them to form rock sockets. A proprietary Roto Loc under-reaming system enabled the work, reducing drilling torque so relatively small rigs could install large-diameter piles in restricted work zones. Battered piles and lateral load testing addressed seismic and other lateral demands, including protection of the existing seawall.<br /><br />Construction also required careful coordination of night-time deliveries, lane closures, utilities, equipment, and barge-based compressors and grout plants. The alternatives helped the project maintain its planned steel-erection milestone despite a two-month late start, redesigns, and added scope. Prefabricated building modules were ultimately placed over the highway during night closures.

Keywords

Rockefeller University

Stavros Niarchos River Campus

mini-caissons

FDR Drive

foundation engineering

rock sockets

under-reaming

Posillico

battered piles

modular construction