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Interface load transfer degradation during cyclic loading: a microscale investigation

Interface load transfer degradation during cyclic loading: a microscale investigation
Interface load transfer degradation during cyclic loading: a microscale investigation

The shaft capacity of piles in sand subjected to cyclic (wave) loading has been observed to decrease significantly with loading cycles (Poulos, 1989). A number of researchers (Boulon and Foray, 1986; Tabucanon et al., 1995; Shahrour et al., 1999) have replicated the characteristics of the load transfer degradation behavior in the laboratory through cyclic interface shear testing with a constant normal stiffness confinement condition (Vesic, 1972). However, no consensus currently exists as to the primary microscale mechanisms that govern cyclic interface shear behavior and load transfer degradation. A research program was undertaken to quantify the contribution of soil properties, cementation, confinement condition, and displacement mode, in load transfer degradation. Monotonie and cyclic interface shear tests were performed using a modified interface direct shear device with a Perspex side window. The specimen particle displacement fields were quantified during selected cycles by capturing high resolution digital images (1600 × 1200 pixels) and using Particle Image Velocimetry (White et al., 2001a). Results indicate that the confinement condition, which is intended to replicate the elastic response of the far-field soil, is of primary importance as it allows for normal stress relaxation with soil contraction adjacent to the interface. The displacement magnitude, particle characteristics, and particle-particle cementation were also observed to affect the magnitude and rate of degradation. It is anticipated that these findings will provide a fundamental rationale to identify field conditions where shear stress degradation is likely to occur and a basis from which more rigorous models may be developed.

CNS, Constant normal stiffness, Cyclic degradation, Cyclic shear, Interface shear, Load transfer, Particle image velocimetry, Particle tracking, Planar deformations (IGC: E12)
0038-0806
81-93
DeJong, Jason T.
f35a93e8-7b73-458c-8c4a-29fa59485437
Randolph, Mark F.
75caa33a-e630-4ae8-84cd-758797bf9633
White, David J.
a986033d-d26d-4419-a3f3-20dc54efce93
DeJong, Jason T.
f35a93e8-7b73-458c-8c4a-29fa59485437
Randolph, Mark F.
75caa33a-e630-4ae8-84cd-758797bf9633
White, David J.
a986033d-d26d-4419-a3f3-20dc54efce93

DeJong, Jason T., Randolph, Mark F. and White, David J. (2003) Interface load transfer degradation during cyclic loading: a microscale investigation. Soils and Foundations, 43 (4), 81-93. (doi:10.3208/sandf.43.4_81).

Record type: Article

Abstract

The shaft capacity of piles in sand subjected to cyclic (wave) loading has been observed to decrease significantly with loading cycles (Poulos, 1989). A number of researchers (Boulon and Foray, 1986; Tabucanon et al., 1995; Shahrour et al., 1999) have replicated the characteristics of the load transfer degradation behavior in the laboratory through cyclic interface shear testing with a constant normal stiffness confinement condition (Vesic, 1972). However, no consensus currently exists as to the primary microscale mechanisms that govern cyclic interface shear behavior and load transfer degradation. A research program was undertaken to quantify the contribution of soil properties, cementation, confinement condition, and displacement mode, in load transfer degradation. Monotonie and cyclic interface shear tests were performed using a modified interface direct shear device with a Perspex side window. The specimen particle displacement fields were quantified during selected cycles by capturing high resolution digital images (1600 × 1200 pixels) and using Particle Image Velocimetry (White et al., 2001a). Results indicate that the confinement condition, which is intended to replicate the elastic response of the far-field soil, is of primary importance as it allows for normal stress relaxation with soil contraction adjacent to the interface. The displacement magnitude, particle characteristics, and particle-particle cementation were also observed to affect the magnitude and rate of degradation. It is anticipated that these findings will provide a fundamental rationale to identify field conditions where shear stress degradation is likely to occur and a basis from which more rigorous models may be developed.

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More information

Published date: 2003
Keywords: CNS, Constant normal stiffness, Cyclic degradation, Cyclic shear, Interface shear, Load transfer, Particle image velocimetry, Particle tracking, Planar deformations (IGC: E12)

Identifiers

Local EPrints ID: 420395
URI: https://eprints.soton.ac.uk/id/eprint/420395
ISSN: 0038-0806
PURE UUID: bb459d75-3389-4daf-9beb-e22ba06b1b8f
ORCID for David J. White: ORCID iD orcid.org/0000-0002-2968-582X

Catalogue record

Date deposited: 04 May 2018 16:31
Last modified: 14 Mar 2019 01:24

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Contributors

Author: Jason T. DeJong
Author: Mark F. Randolph
Author: David J. White ORCID iD

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