Ground Information for Pile Design in London Clay - A Review of Current Practice

It is estimated that every year the design of thousands of bored piles constructed in London Clay in London and the Home Counties rely on the recommendations of the LDSA ‘Guidance Notes for the Design of Straight Shafted Bored Piles in London Clay’ (LDSA, 2017). First published in 1999 the Guidance Note has had two revisions, the most recent in 2017. The heart of the Guidance Note is an empirically based bored pile design method that relates pile capacity to the undrained shear strength of the London Clay. The undrained shear strength should be obtained using the carefully prescribed soil sampling and testing process set out in the Guidance Note. This paper reviews ground information received for over thirty London Clay bored piling projects encountered between 2017 and 2019 and provides a useful insight into the quality and compliance with the LDSA recommendations of ground information frequently provided to pile designers.