Modeling of shear stiffness reduction from database of axial load tests on pile foundations

Initiating at the small-strain shear modulus (Gmax), the mechanical nonlinear stress-strain-strength behavior of soil manifests in the form of modulus reduction, typically expressed in normalized form as Gop/Gmax. Here, Gop is the operative shear modulus – a reduced stiffness value corresponding to...

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Main Authors: Niazi Fawad S., Mayne Paul W.
Format: Article
Language:English
Published: EDP Sciences 2019-01-01
Series:E3S Web of Conferences
Online Access:https://www.e3s-conferences.org/articles/e3sconf/pdf/2019/18/e3sconf_isg2019_13002.pdf
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author Niazi Fawad S.
Mayne Paul W.
author_facet Niazi Fawad S.
Mayne Paul W.
author_sort Niazi Fawad S.
collection DOAJ
description Initiating at the small-strain shear modulus (Gmax), the mechanical nonlinear stress-strain-strength behavior of soil manifests in the form of modulus reduction, typically expressed in normalized form as Gop/Gmax. Here, Gop is the operative shear modulus – a reduced stiffness value corresponding to strain levels that the soil is experiencing. Assessment of Gop is critical to reliable predictions of load-related deformations within the soil. Among the various categories of loading, deep foundations and pilings exhibit a typical mechanism of axial load transfer to the foundation soil. For friction type piles, the stiffness reduction mostly takes place along the pile shaft-soil interface. Within the framework of an analytical solution, the back analyses from the results of load tests on pile foundations, together with the knowledge of pile geometries and soil parameters, provide an outline for evaluation of Gop at different load increments. This paper explains the methodology employed to develop stiffness reduction curves (Gop/Gmax) as a function of pseudo-strain (γp = wt/d), where, wt = settlement at the pile top, and d = pile diameter. Algorithms that integrate the plasticity characteristics of the soil are also presented. The results afford an improved evaluation of the complete nonlinear load-settlement (Q-wt) response for pile foundations under axial loads.
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spelling doaj.art-c0ba1ab299294b14af6aa6bd71b120692022-12-21T23:01:21ZengEDP SciencesE3S Web of Conferences2267-12422019-01-01921300210.1051/e3sconf/20199213002e3sconf_isg2019_13002Modeling of shear stiffness reduction from database of axial load tests on pile foundationsNiazi Fawad S.Mayne Paul W.Initiating at the small-strain shear modulus (Gmax), the mechanical nonlinear stress-strain-strength behavior of soil manifests in the form of modulus reduction, typically expressed in normalized form as Gop/Gmax. Here, Gop is the operative shear modulus – a reduced stiffness value corresponding to strain levels that the soil is experiencing. Assessment of Gop is critical to reliable predictions of load-related deformations within the soil. Among the various categories of loading, deep foundations and pilings exhibit a typical mechanism of axial load transfer to the foundation soil. For friction type piles, the stiffness reduction mostly takes place along the pile shaft-soil interface. Within the framework of an analytical solution, the back analyses from the results of load tests on pile foundations, together with the knowledge of pile geometries and soil parameters, provide an outline for evaluation of Gop at different load increments. This paper explains the methodology employed to develop stiffness reduction curves (Gop/Gmax) as a function of pseudo-strain (γp = wt/d), where, wt = settlement at the pile top, and d = pile diameter. Algorithms that integrate the plasticity characteristics of the soil are also presented. The results afford an improved evaluation of the complete nonlinear load-settlement (Q-wt) response for pile foundations under axial loads.https://www.e3s-conferences.org/articles/e3sconf/pdf/2019/18/e3sconf_isg2019_13002.pdf
spellingShingle Niazi Fawad S.
Mayne Paul W.
Modeling of shear stiffness reduction from database of axial load tests on pile foundations
E3S Web of Conferences
title Modeling of shear stiffness reduction from database of axial load tests on pile foundations
title_full Modeling of shear stiffness reduction from database of axial load tests on pile foundations
title_fullStr Modeling of shear stiffness reduction from database of axial load tests on pile foundations
title_full_unstemmed Modeling of shear stiffness reduction from database of axial load tests on pile foundations
title_short Modeling of shear stiffness reduction from database of axial load tests on pile foundations
title_sort modeling of shear stiffness reduction from database of axial load tests on pile foundations
url https://www.e3s-conferences.org/articles/e3sconf/pdf/2019/18/e3sconf_isg2019_13002.pdf
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