Fiona Chow, research assistant, Imperial College, University of London, UK. This paper was first published in GE’s July/August 1995 edition.
A study of the stress interactions between two adjacent piles has been conducted in a dense sand deposit at Dunkirk, north France. A heavily instrumented model pile was used to record the effective stress changes induced by the installation of a second pile 4.5 pile diameters away. The measurements during installation and the effects on load carrying capacity are presented. The neighbouring pile installation produced a large increase in shaft capacity and a reduction in base contribution and stifiness. Comparisons are made with the results of previous studies involving field and laboratory tests and the implications of the changes in behaviour are discussed.