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Piled foundations in weak rocks (R181)

Piling in weak rocks presents particular problems to the foundation designer and piling specialist, not least because of the difficulty of investigating and testing these intermediate geomaterials. There is a lack of understanding of their behaviour, especially of their deformability and changes in their properties during pile installation. As a consequence, design methods may be over-conservative and assessments of design parameters too pessimistic. Also, the lack of a flexible and robust procurement process has in the past led to uneconomic design and contractual disputes during construction. This book summarises current knowledge and practice. It provides a definition of weak rock, and considers the nature of the material and the best ways of investigating, characterising and classifying weak rock for the purpose of pile design. Four published design methods are examined, with worked examples. Five case studies illustrate the main points of the report and are complemented by an extensive bibliography.

The work concludes with recommendations for improving practice and enhancing economy through appropriate geotechnical modelling, pile selection, pile design and procurement. Of these recommendations, the need for improved communications between the structural designer, pile designer and piling contractor is particularly emphasised. There are also some useful suggestions about directions for future research.

'Piled foundations in weak rocks' will prove to be a valuable reference for geotechnical and structural engineers working in investigation, design and construction, and research.

Key words: ground engineering, piling, ground investigation and characterisation.

ISBN: 978-0-86017-494-3
Author: J A Gannon, G G T Masterton, W A Wallace et al
Number of pages: 140 (paperback)
Publisher: CIRIA
Date of Publication: November 1999