Displacement-pile behaviour in a soft marine clay

Abstract

The paper presents the results of field experiments performed using the Imperial College instrumented displacement pile in a soft, sensitive marine clay at Bothkennar, Scotland. These results are compared with data from similar programmes of experiments performed in other clay types with this pile so that some of the major factors controlling displacement-pile performance may be identified. Key words : displacement pile, instrumentation, sensitive clay, effective stress design.

Shaft Capacity of Open-Ended Piles in Clay

“…This stress reduction, known as relaxation, is a common feature of displacement pile behavior in clay (see Bond 1991, Lehane andJardine 1994 andothers).…”

“…Ground conditions at the site load tests were performed within 3 to 12 hours after the end of driving, whilst tension tests were performed within 3 hours of the compression tests, resulting in all load tests being essentially undrained. Pile tests performed in the nearby Cowden Till (Lehane et al 1994) which has a similar geological history suggest that less than 5% of the excess pore pressure generated during installation would have dissipated prior to the load tests. A delay before testing the pile at a penetration depth of 6 m caused the results of this test to be omitted from consideration herein.…”

Distributed fibre-optic monitoring of an Osterberg-cell pile test in London

“…Pile load tests are vital for understanding the actual field behaviour of piles and for determining the relevant geotechnical parameters (Lehane & Jardine, 1994;Seo et al, 2013;Bica et al, 2014). Appropriate instrumentation is crucial so that useful and reliable values for such aforementioned parameters are obtained for the designers (Coop & Wroth, 1989;Randolph, 2003;McCabe & Lehane, 2006).…”

The Shaft Capacity of Displacement Piles in Clay: A State of the Art Review

“…It is apparent that additional testing of large diameter, high capacity piles ,where radial effective stresses are measured throughout installation, equalisation and load-testing, is required in order to address many of the uncertainties that remain in current pile design methods. Undrained Strength, s u (kPa) Adhesion Factor, α Tomlinson(1957) Peck (1958) Woodward (1961) Kerisel ( Tomlinson(1957)   λ approach, Vijayvergiya and Focht (1972)   API 1(1976API 1( -1986   API 2(1976API 2( -1986   Semple and Rigden (1984)   Randolph and Murphy (1985)   API(1987-Present)   Kolk & van der Velde (1996)   NGI-99, Karlsrud et al (2005)   Lehane and Jardine (1994a) Bothkennar Low OCR shallow marine clay Lehane and Jardine (1994b) Pentre Low OCR Glacio-Lacustrine silty clay Chow (1997) …”