Underground Expansion of a 27-year old Cultural Centre Excavation and Foundation Reuse Concerns

This paper addresses the geotechnical, structural and construction issues, with emphasis on the geotechnical issues, which had to be taken into consideration in the 2005 basement construction below a 930m 2 one-storey Cultural Centre supported primarily by cast-in-place (bored) concrete piles. The Cultural Centre was constructed in 1978 with a partial basement and extensions undertaken beneath its footprint in 1984 and 1993. Due to the unavailability of the original geotechnical report a new geotechnical investigation was undertaken from which capacities were evaluated for the original piles, as well as for the piles influenced by the proposed basement construction. After much discussion, which included the use of helical piles to enhance the capacity of the existing piles, spread footings were constructed around a few critical piles. Basement construction has since been completed without any problems. This case study demonstrates some of the concerns in reusing existing foundations, when design and construction records are unavailable.