City Research Online

Design method for the 'impression pile'

Lalicata, L. M., Stallebrass, S. E. ORCID: 0000-0002-3747-9524, McNamara, A. M. ORCID: 0000-0002-3452-0800 and Panchal, J. P. (2021). Design method for the 'impression pile'. Proceedings of the Institution of Civil Engineers: Geotechnical Engineering, doi: 10.1680/jgeen.21.00033

Abstract

Urban development in congested cities requires a better exploitation of the available surface, leading to taller structures. These buildings are usually founded on piles that have to be increased in dimension to accommodate the larger loads, resulting in increases in both the cost and the carbon dioxide footprint of the pile foundation. An alternative option is to improve pile performance by enhancing the shaft capacity, which is commonly the most important factor in determining the ultimate capacity of a pile constructed in a clay soil subjected to axial load. For piles in stiff clays such as London Clay, the soil-pile friction may be increased by profiling the side walls of a bored cast in situ pile with small discrete 'impressions' such that the latter form nodules on the shaft of the concreted pile. Centrifuge tests carried out at City, University of London, and field trials undertaken by Keltbray Piling across different London sites showed an increase in the shaft capacity of around 40%. In this work, a simple design method based on experimental evidence and an existing plastic failure mechanism was derived for 'impression' piles. The proposed method shows good agreement with data and enables a direct prediction of the increase in capacity for future designs.

Publication Type: Article
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Departments: School of Mathematics, Computer Science & Engineering > Engineering > Civil Engineering
Date available in CRO: 06 Dec 2021 12:03
Date deposited: 6 December 2021
Date of acceptance: 22 April 2021
Date of first online publication: 23 September 2021
URI: https://openaccess.city.ac.uk/id/eprint/27174
[img] Text - Accepted Version
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