Measurement of stresses around closed-ended displacement piles in sand

Abstract

Jardine, R. J. et al. Géotechnique [http://dx.doi.org/10.1680/geot.9.P.137] 1 Measurement of stresses around closed-ended displacement piles in sand R. J. JAR DINE Ã , B. T. ZHU †, P. FORAY ‡ and Z. X. YANG § Calibration chamber experiments are reported that investigate the evolution of stresses around closedended, highly instrumented, model displacement piles during simulated driving into a heavily instrumented sand mass. The soil stresses are shown to vary spatially relative to the pile tip location. As well as showing considerable radial variation, the stresses developed at any given depth build sharply as the tip approaches, and reduce rapidly as it passes. Clear differences are evident between the behaviours seen close to the shaft during alternate penetration and pause periods. Load-cycling effects are most significant close to the shaft, where the local stress paths indicate a tendency for constrained 'dilatant' behaviour, with radial stresses increasing, during loading. In contrast, markedly 'contractant' radial stress reductions are evident on unloading.

Advanced laboratory testing in research and practice: the 2nd Bishop Lecture

“…Advanced laboratory testing in research and practice: the 2nd Bishop Lecture Jardine Rimoy (2013) describes more recent experiments with the same equipment, noting that axial capacities from multiple load tests agree encouragingly well with predictions made with the 'fieldcalibrated' capacity approach outlined by Jardine et al (2005b), which gave good results for the Dunkerque field tests. Jardine et al (2013aJardine et al ( , 2013b report and interpret the measurements made during installation, referring to these as the 'mini-ICP data set'. Pile penetration invoked extreme stress changes in all three normal stress components and significant stress changes out to r/R > 33.…”

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

“…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). Although a wealth of pile top load-displacement curves is nowadays available (Jardine et al, 2013a(Jardine et al, , 2013bYang et al, 2014), the ability to acquire information along the pile depth opens more opportunities for studying the real pile-soil interaction behaviour.…”

Theoretical breakage mechanics and experimental assessment of stresses surrounding piles penetrating into dense silica sand

“…2 compares the post-penetration GSD curves defined in three zones around the pile with theoretical predictions. Further aspects of the latter experiments have been reported by Jardine et al (2013aJardine et al ( , 2013b, who conducted careful comprehensive measurements of the stress distributions developed on and around an instrumented pile. Yang et al (2014) offer a broad review of how these data compare with related predictions made with a range of theoretical approaches and also of data gathered in other experimental studies.…”

“…Yang et al (2014) offer a broad review of how these data compare with related predictions made with a range of theoretical approaches and also of data gathered in other experimental studies. This letter sets out detailed predictions made using the approach of Zhang et al (2013) for the calibration chamber stress measurements of Jardine et al (2013aJardine et al ( , 2013b. The new stress predictions were made without altering the breakage mechanics model parameters or finite-element (FE) analytical procedures reported by Zhang et al (2013).…”