Sheet pile groups as an alternative foundation solution to cast in-situ concrete piles

Concrete piles have become a common high load bearing foundation solutions providing end bearing and frictional resistance along the shaft. They are typically used for founding commercial or residential blocks with a design life of approximately 50 years. Following this the superstructure is decommissioned and may be demolished. However, piles are difficult to remove and therefore future developers can incur significant expense and programme delays in preparing the site to avoid obstructions. If removed, concrete piles are required to be broken down which is a slow and laborious process. However, a foundation solution has been developed that allows foundations to be installed and extracted with relative ease whilst still achieving a similar, if not improved capacity. This solution has been defined as a hybrid foundation comprising deep sheet piles for shaft resistance and a pile cap as a shallow foundation. The hybrid pile offers significant advantages over concrete piles include ease of installation, extraction, reuse and economy. Axial capacity of individual sheet piles is low, however geometrically arranging sheet piles; was shown to offer comparable or improved capacity over conventional concrete piles. The results from a series of centrifuge tests are presented in this paper.