Characterisation of the effects of time on the shaft friction of displacement piles in sand

Lim, Jit Kheng; Lehane, Barry

doi:10.1680/geot.13.p.220

Cited by 47 publications

(11 citation statements)

References 33 publications

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“…In keeping with the contention discussed previously and proposed by Lim and Lehane (2014b) that the disturbance caused by installation is the primary factor giving rise to ageing and pile set-up, a range of different factors were examined for the database of Shenton Park tests. The most consistent trend emerged for the 'short term' capacity (taken as the capacity developed between 1 day and 7 days) when this disturbance was quantified as the number of blows or jacking cycles per unit external area of pile shaft (N bA ).…”

Section: Shenton Park Field Test Databasementioning

confidence: 99%

“…However evidence such as that provided by Lim and D r a f t involved first time tension loading of pipe piles installed using three impact/vibration installation modes. The tests were performed at the Shenton Park sand site where there has been a considerable number of previous pile tests with different installation modes (Lehane 2008;Lim 2013;Schneider 2007;Xu 2007). This paper presents a comparison of the trends from all Shenton Park tests and first-time tension tests from other sand sites, enabling conclusions to be drawn regarding the relationship between shaft capacity, installation mode and set-up time.…”

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confidence: 99%

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Evaluation of installation effects on set-up of field displacement piles in sand

et al. 2019

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The paper presents results from a new series of tests on displacement piles in sand, involving different installation modes, and combines these with results from previous tests at the same site as well as with test data at two other well-investigated sand sites to provide fresh insights into factors affecting “short-term” capacity and set-up of shaft friction. It is shown that the shaft capacity measured shortly after installation reduces systematically with the logarithm of the number of impact blows or jacking increments per unit shaft area imparted during installation. However, the degree of set-up of shaft friction for piles increases with an increase in the number of blows, and piles installed using a large number of blows can attain highest “long-term” shaft capacities, despite having the lowest short-term capacity. The tests indicated that the driving impact frequency had a relatively small influence on shaft friction, while piles installed by vibration attain short-term capacities comparable to driven impact piles, but showed negative set-up.

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Section: Shenton Park Field Test Databasementioning

confidence: 99%

mentioning

confidence: 99%

Evaluation of installation effects on set-up of field displacement piles in sand

et al. 2019

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“…Although the experiments show that rate of capacity gain with time for the driven piles is generally higher than that of the jacked piles, this trend is less obvious than seen in the field by Lim (2013), who found much higher relative increases in capacity with time for the driven piles. Such a difference is likely to be associated with predominant influence of dilation on the capacity of small model piles.…”

Section: Effect Of the Pile Installation Methodsmentioning

confidence: 63%

Set-up of pile shaft friction in laboratory chamber tests

Lim

Lehane

2014

International Journal of Physical Modelling in Geotechnics

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Although field evidence of increases in pile shaft friction over time (i.e. set-up) in sand is compelling, the observations are highly scattered and the mechanisms leading to the increases are poorly understood. Several attempts have been made to model the phenomenon using small-scale physical models in a controlled environment, but the investigations were hampered by numerous restrictions. This paper describes an improved small-scale model pile experiment designed to investigate the ageing effects of pile shaft friction in sand. Details of the experimental set-up adopted and procedures employed are presented. Results show that the phenomenon of pile set-up is successfully modelled and that load-displacement characteristics are in keeping with those observed in centrifuge tests. Although the ageing effects observed in this laboratory-scale physical model may not be directly applicable to field scale piles, comparative studies involving various influential parameters provide qualitative indications of the relative influence of a variety of parameters on the phenomenon.

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“…There is renewed interest in recent years in the gain of bearing capacity in both sands and clays (e.g., Lehane and Jardine 1994;Chow et al 1998;Axelsson 2000;Hunt et al 2002;Bullock et al 2005a, b;Fellenius 2008;Karlsrud et al 2014;Lim and Lehane 2014;Haque et al 2016). The numerical efforts so far have been focused on the pile-setup stage (e.g., Randolph et al 1979;Whittle and Sutabutr 1999;Basu et al 2014;Abu-Farsakh et al 2015), linking the (undrained) pile installation and dissipation of excess pore pressures.…”

Section: Introductionmentioning

confidence: 99%

“…The link with pile installation suggests that the process is largely a strength-recovery process from the disturbances of pile installation, rather than a principal gain in capacity only (e.g., Lim and Lehane 2014). Therefore, the process is not as often studied numerically because the soil disturbances from the installation process need to be incorporated in the analyses.…”

Section: Introductionmentioning

confidence: 99%

Modeling Aging of Displacement Piles in Natural Soft Clay

Karlsson

Yannie

Dijkstra

2019

J. Geotech. Geoenviron. Eng.

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A multitude of mechanisms will affect the evolution of the pile response over time, each with their respective time scale. It is shown that most of the processes can be linked to the pile installation stage, which alters the soil surrounding the pile. As a result, there is a change in the mechanical properties of the soil that will influence the subsequent pile response over time. These long-term mechanisms include the dissipation of excess pore pressures from pile installation and the creep in the soil. This paper presents a numerical approach that combines the strain-path method, an advanced effective stress-based constitutive model for soft soils, and a multiphase numerical framework that enables the modeling of the pile installation and subsequent change of pile bearing capacity over time. The presented results demonstrate that the degree of remolding of the soil during the pile installation stage is closely linked to the subsequent pile response. For the Onsøy test case studied, the increase in shaft capacity over time, demonstrated to be linked to undrained strength recovery, could be faithfully reproduced during and after dissipation of excess pore pressures. Hence, pile aging of displacement piles installed in clay is strongly linked to installation effects and the creep and relaxation processes in the soil. Further study is required to fully reveal the physicochemical mechanisms that underpin these processes.

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Characterisation of the effects of time on the shaft friction of displacement piles in sand

Cited by 47 publications

References 33 publications

Evaluation of installation effects on set-up of field displacement piles in sand

Evaluation of installation effects on set-up of field displacement piles in sand

Set-up of pile shaft friction in laboratory chamber tests

Modeling Aging of Displacement Piles in Natural Soft Clay

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