Design of Piles in London Clay from Three Test Piles in Paddington: A Case Study

There is still debate about pile design methods in London Clay, which should be one of the most understood materials in the world. There is, for instance, little consensus about effects of the method of construction, the diameter and length. Contractors who construct at the smaller end of the diameter spectrum are more prepared to use higher alpha values.

Design methods are currently based on the results from a single source data base. This paper puts into the public domain the results of three tests of CFA and rotary bored piles of varying diameters, also deriving the implied total stress design factors against a comprehensive amount of site investigation data.

Geotechnical data for most sites was of reasonable quality and additional information has been collated from other developments in the area. The stratigraphy is consistent and this allows the interpretation of test data against both the site specific data and the “average” for the area.