A Novel Method for Assessing the Reuse of Under Reamed Piles as Part of the Southbank Place Project-PPT Presentation

PPT Presentation

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The Southbank Place project investigated whether existing under-reamed piles beneath the Shell Centre site could be reused for a major new development. Reuse was considered both necessary and preferable to installing entirely new foundations.<br /><br />The assessment began with a review of historic site information, including ground investigations, pile layouts and geometries, and published design material. Although construction records and original calculations were unavailable, archive drawings provided proposed pile dimensions and toe levels. The review also considered the site’s complex history, including nearby London Underground tunnels and previous construction and excavation.<br /><br />To address uncertainties about pile presence, length, position, dimensions, concrete condition and performance, six representative piles were selected for investigation. The sample size was informed by ISO 2859-1:1999, adapted to the project’s circumstances. Intrusive works, including inclined and vertical coring, were used to verify pile geometry and condition.<br /><br />Reuse was then assessed against the proposed development and new foundation design. The team developed a detailed three-dimensional soil–structure interaction model, representing existing under-reamed piles and proposed new piles. Staged finite-element analysis accounted for the site’s stress history, past construction, groundwater changes and soil–structure interaction. The modelling assessed existing and proposed loads on the piles and informed substructure design and settlement estimates.<br /><br />Because standard BRE/CIRIA guidance did not directly address under-reamed piles, its methodology was adapted for the project. The overall approach combined historic research, targeted intrusive investigation and sophisticated analysis to establish whether the existing foundations could safely contribute to the new development.

Keywords

Southbank Place

Shell Centre

under-reamed piles

pile reuse

foundation assessment

ground investigations

soil-structure interaction

finite-element analysis

intrusive coring

substructure design