Analysis and Design of Piled Geogrid-Reinforced-Earth Embankment

A pile-supported geogrid-reinforced-earth embankment was designed and constructed to serve as an access road for heavily loaded cranes and pile-installation rigs for constructing a major bridge between New York and New Jersey in the United States. The road is to also serve as an access to maintain the bridge during its service life. Subsurface investigations performed along the proposed access road alignment revealed subsurface conditions typically consisting of surficial fill underlain by a highly compressible organic clay and/or peat overlying marine sand underlain by glacial till. A limiting-settlement criterion set forth by the crane engineer together with settlement and slope-stability analyses indicated a conventional embankment could experience non-tolerable settlement and slope instability where thick organic soils were encountered. A ground-improvement program was carried out using geogrid reinforcement, a load transfer platform (LTP), and timber elements to control settlement and enhance slope stability. Where thinner organic soils were encountered, staged construction and a monitoring program were implemented to design and construct the proposed embankment.