Publication Abstract

Proceedings - Fourth International Conference - Piling and Deep Foundations, 1991, Stresa, Italy, (DFI)

72 Geotechnical instrumentation for a full-scale study of negative skin friction in soft clay
J.A. Little & K. Ibrahim Department of Civil Engineering, Heriot-Watt University, Edinburgh, UK G. Price Geotechnics Division, Building Research Establishment, Garston, Watford, UK

Downdrag forces on piles can be large, and in extreme cases downdrag has resulted in bearing failure of entire groups of piles. In the past, studies on downdrag have concentrated on investigations concerning single piles in both the laboratory and at full-scale. As far as is known, no full-scale study has been carried out to investigate the effects of downdrag in pile groups. The paper describes such a study currently underway at Grangemouth, Scotland. Here, two groups of 406mm diameter, 20m length concrete displacement shell piles have been constructed in soft clay. One (end-bearing) group of piles has been driven onto gravel; the other (friction) group has been driven to lie slightly above the gravel. Each group has two single control piles associated with it. Two of the four control piles are slip coated. Within each group, piles are instrumented for axial load, total lateral pressure and pore water pressure. Details are given of this instrumentation in terms of its design and procedures for its installation.

 article #510; publication #37 (IC-1991-IT)