Long-term pile testing in London Clay: a case study

This paper describes how a series of large-diameter auger-bored test piles were constructed for the Terminal Five development at London's Heathrow Airport. The piles were tested over a period of one year, prior to the start of the permanent works, to investigate how the shaft resistance within the London Clay varies with time. The test procedure is described, and some of the results are presented and briefly discussed. A further two piles were constructed to investigate the base resistance in the London Clay at depths of up to 47 m. Osterberg Cells were used to generate the testing force, and the construction and testing of these piles is also discussed in the paper.