Unconditional convergence of theoretical solutions to u-p formulation

Dynamic soil-water coupling analyses, based on the u-p formulation, are inapplicable to highly permeable soils, causing numerical instability. In this study, it is demonstrated that theoretical solutions to the u-p formulation itself certainly exhibit unconditional convergence regardless of the perm...

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Main Authors: Tomohiro Toyoda, Toshihiro Noda
Format: Article
Language:English
Published: Elsevier 2024-02-01
Series:Soils and Foundations
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S0038080623001506
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author Tomohiro Toyoda
Toshihiro Noda
author_facet Tomohiro Toyoda
Toshihiro Noda
author_sort Tomohiro Toyoda
collection DOAJ
description Dynamic soil-water coupling analyses, based on the u-p formulation, are inapplicable to highly permeable soils, causing numerical instability. In this study, it is demonstrated that theoretical solutions to the u-p formulation itself certainly exhibit unconditional convergence regardless of the permeability coefficient. This suggests that the instability is only numerical and can be observed in a temporally discretized system. Firstly, the linearized governing equation for the u-p formulation was proven to be reduced to a damped wave equation under a one-dimensional condition, similar to the Full formulation. Secondly, theoretical solutions for the u-p formulation were derived and their unconditional convergence was confirmed. Then, the essential characteristics of the u-p theoretical solutions, that is, the underestimation of permeability, overestimation of compression wave celerity, and occurrence of negative pore water pressure against positive load application, were described and compared with theoretical solutions for the Full formulation.
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spelling doaj.art-627ea127af144f7c83f89c7bef002b732024-02-17T06:37:09ZengElsevierSoils and Foundations2524-17882024-02-01641101421Unconditional convergence of theoretical solutions to u-p formulationTomohiro Toyoda0Toshihiro Noda1Corresponding author.; Nagoya University, JapanNagoya University, JapanDynamic soil-water coupling analyses, based on the u-p formulation, are inapplicable to highly permeable soils, causing numerical instability. In this study, it is demonstrated that theoretical solutions to the u-p formulation itself certainly exhibit unconditional convergence regardless of the permeability coefficient. This suggests that the instability is only numerical and can be observed in a temporally discretized system. Firstly, the linearized governing equation for the u-p formulation was proven to be reduced to a damped wave equation under a one-dimensional condition, similar to the Full formulation. Secondly, theoretical solutions for the u-p formulation were derived and their unconditional convergence was confirmed. Then, the essential characteristics of the u-p theoretical solutions, that is, the underestimation of permeability, overestimation of compression wave celerity, and occurrence of negative pore water pressure against positive load application, were described and compared with theoretical solutions for the Full formulation.http://www.sciencedirect.com/science/article/pii/S0038080623001506Soil-water couplingu-p formulationUnconditional convergence
spellingShingle Tomohiro Toyoda
Toshihiro Noda
Unconditional convergence of theoretical solutions to u-p formulation
Soils and Foundations
Soil-water coupling
u-p formulation
Unconditional convergence
title Unconditional convergence of theoretical solutions to u-p formulation
title_full Unconditional convergence of theoretical solutions to u-p formulation
title_fullStr Unconditional convergence of theoretical solutions to u-p formulation
title_full_unstemmed Unconditional convergence of theoretical solutions to u-p formulation
title_short Unconditional convergence of theoretical solutions to u-p formulation
title_sort unconditional convergence of theoretical solutions to u p formulation
topic Soil-water coupling
u-p formulation
Unconditional convergence
url http://www.sciencedirect.com/science/article/pii/S0038080623001506
work_keys_str_mv AT tomohirotoyoda unconditionalconvergenceoftheoreticalsolutionstoupformulation
AT toshihironoda unconditionalconvergenceoftheoreticalsolutionstoupformulation