Design Methods for Driven Piles in Sand and Clay
Dr Fiona Chow
Studies have show that out of all of the components of an offshore structure, the design of the foundations contains the most uncertainty. Although methods of pile construction have made enormous advances over the last 50 years, the advances in pile design have been more muted and acceptance of these advances has been slower. Recognising that there are limitations to the traditional design methods, the American Petroleum Institute (API) and ISO have included new alternative CPT methods for the design of piles in sand in their international design recommendations.
The presentation will describe the Imperial College Pile (ICP) design methods, also known as the MTD design methods. These were developed over a ten year period involving three PhD projects (Bond, 1989; Lehane, 1992 and Chow, 1997) encompassing detailed field investigations, laboratory testing, analysis and verification against a large database of piles in sand and clay. The verification studies showed that the new design methods were more reliable than traditional methods delivering cost savings or improvements in foundation safety.
In 1996 the design methods were published in “New Design Methods for Offshore Piles”. This was updated in 2005 in “ICP Design Methods for Driven Piles in Sands and Clays”, published by Thomas Telford. The results have been applied on offshore, nearshore and onshore projects from Azerbaijan to Venezuela. The talk will also refer to the effects of pile group installation and changes in pile capacity with time (pile ageing) with illustrations from case histories.
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