Abstract:
Urban development in congested cities requires a better exploitation of the available surface, leading to
taller structures. These buildings are usually founded on piles that have to be increased in dimension to
accommodate the larger loads. Consequently, both the cost and the carbon footprint of the pile foundations
rises. An alternative option is to improve pile performance by enhancing shaft capacity, which is commonly
the most important factor in determining the ultimate capacity of a pile constructed in a clay soil subjected
to axial load. For piles in stiff clays, such as London Clay, the soil/pile friction may be increased by profiling
the side walls of a bored cast in situ pile with small discrete “impressions†such that the latter form nodules
on the shaft of the concreted pile. The results from centrifuge and full scale field tests showed that the
impression pile represents a viable technology to enhance the shaft capacity as they provide an increase in
capacity of 40%. Alternatively, reduced length impression pile can be used. This paper explores the
implications of the impression pile technology on the potential carbon saving.