This is the published version of the paper.This version of the publication may differ from the final published version. This research concerns the influence of ribs on the ultimate capacity of a bored pile in overconsolidated clay. Ribbed bored piles are known to give increased shaft capacity in comparison to conventional straight-shafted bored piles. The investigation seeks to explore the effectiveness of ribs at increasing the ultimate capacity of a pile, and furthermore to understand how this enhanced capacity is derived. The scale pile test results are analysed using several industry standard methods. A plastic failure envelope for the base of the pile rib is identified. This plastic failure envelope is used to provide a detailed design solution for the ultimate capacity of a ribbed pile. The design solution is simple and requires a summation of the constitutive contributions from each rib and from the base and shaft of the pile. This method has been used successfully to predict the ultimate capacity of any pile tested to within ±8%. Permanent repository link

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This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link:

The construction of deep basements in urban areas is associated with many risks and problems among Which is the possible damage to existing structures and services resulting from settlements near the excavation. A number of methods are routinely employed to attempt to control these movements (e.g. top-down construction, use of stiff diaphragm walls). This paper discusses the methodology and practicalities of a series of centrifuge model tests designed to investigate the effect of deep basement construction. Two sets of experimental apparatus are described in detail and their effectiveness in terms of robustness and generation of repeatable data are assessed. It is shown that using relatively simple techniques and equipment it is possible to model many of the features associated with top-down construction.

This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link Number of words in main text and tables:5138 words Number of figures: figures AbstractThis paper describes the concept and field testing of a 1200mm diameter x 30m deep hollow cast in situ rotary bored pile foundation. The aim of the foundation is to allow large diameter piles to be constructed using less concrete than in an equivalent conventional solid pile and with a view to allowing reuse at a later date. Reuse is made possible because the hollow core of the pile allows access for inspection after demolition of an existing structure. The new piles may also allow modification to enhance load capacity by augering through the base and extending their length. In addition, the piles are better suited than conventional piles for use as 'energy piles' to allow environmentally friendly heating and cooling. The geotechnical performance of the hollow test pile was comparable with a conventional solid pile constructed during the same trial. Details of construction are given including lessons learned.• A list of notations, defining all of the symbols used.•