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Probabilistic failure envelopes of strip foundations on soils with non-stationary characteristics of undrained shear strength

Probabilistic failure envelopes of strip foundations on soils with non-stationary characteristics of undrained shear strength
Probabilistic failure envelopes of strip foundations on soils with non-stationary characteristics of undrained shear strength

This paper investigates probabilistic failure envelopes of strip foundations on spatially variable soils with profiles of undrained shear strength su linearly increasing with depth using the lower bound random finite element limit analysis. The spatially variable su is characterised by a non-stationary random field with linearly increasing mean and constant coefficient of variation (COV) with depth. The deterministic uniaxial capacities and failure envelopes are firstly derived to validate numerical models and provide a reference for the subsequent probabilistic analysis. Results indicate that the random field parameters COVsu (COV of su) and Δ (dimensionless autocorrelation distance) have a considerable effect on the probabilistic normalised uniaxial capacities which alters the size of probabilistic failure envelopes. However, COVsu and Δ have an insignificant effect on the shape of probabilistic failure envelopes is observed in the V-H, V-M and H-M loading spaces, such that failure envelopes for different soil variabilities can be simply scaled by the uniaxial capacities. In contrast to COVsu and Δ, the soil strength heterogeneity index κ = μkB/μsu0 has the lowest effect on the probabilistic normalised uniaxial capacity factors but the highest effect on the shape of the probabilistic failure envelopes. A series of expressions are proposed to describe the shape of deterministic and probabilistic failure envelopes for strip foundations under combined vertical, horizontal and moment (V-H-M) loading.

bearing capacity, failure, failure envelopes, footings/foundations, probabilistic analysis, random finite element, shallow foundations, soil spatial variability, sparse polynomial chaos expansion/global sensitivity analysis, spatial variability
0016-8505
Gourvenec, Susan
6ff91ad8-1a91-42fe-a3f4-1b5d6f5ce0b8
Shen, Zhichao
bb76dad2-f5c2-455f-895b-597ecb9e302e
Pan, Qiujing
247c86e7-0d19-44b7-aa7d-9fd42877e8ec
Chian, Siau Chen
e853a5c3-ec98-43a0-a69d-2958a3533467
Tian, Yinghui
a5e5f5ae-4280-472b-8bce-07a207c066d6
Gourvenec, Susan
6ff91ad8-1a91-42fe-a3f4-1b5d6f5ce0b8
Shen, Zhichao
bb76dad2-f5c2-455f-895b-597ecb9e302e
Pan, Qiujing
247c86e7-0d19-44b7-aa7d-9fd42877e8ec
Chian, Siau Chen
e853a5c3-ec98-43a0-a69d-2958a3533467
Tian, Yinghui
a5e5f5ae-4280-472b-8bce-07a207c066d6

Gourvenec, Susan, Shen, Zhichao, Pan, Qiujing, Chian, Siau Chen and Tian, Yinghui (2021) Probabilistic failure envelopes of strip foundations on soils with non-stationary characteristics of undrained shear strength. Géotechnique. (doi:10.1680/jgeot.21.00169).

Record type: Article

Abstract

This paper investigates probabilistic failure envelopes of strip foundations on spatially variable soils with profiles of undrained shear strength su linearly increasing with depth using the lower bound random finite element limit analysis. The spatially variable su is characterised by a non-stationary random field with linearly increasing mean and constant coefficient of variation (COV) with depth. The deterministic uniaxial capacities and failure envelopes are firstly derived to validate numerical models and provide a reference for the subsequent probabilistic analysis. Results indicate that the random field parameters COVsu (COV of su) and Δ (dimensionless autocorrelation distance) have a considerable effect on the probabilistic normalised uniaxial capacities which alters the size of probabilistic failure envelopes. However, COVsu and Δ have an insignificant effect on the shape of probabilistic failure envelopes is observed in the V-H, V-M and H-M loading spaces, such that failure envelopes for different soil variabilities can be simply scaled by the uniaxial capacities. In contrast to COVsu and Δ, the soil strength heterogeneity index κ = μkB/μsu0 has the lowest effect on the probabilistic normalised uniaxial capacity factors but the highest effect on the shape of the probabilistic failure envelopes. A series of expressions are proposed to describe the shape of deterministic and probabilistic failure envelopes for strip foundations under combined vertical, horizontal and moment (V-H-M) loading.

Text
Shen et al. 2021_Geotechnique_Author version - Accepted Manuscript
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More information

Accepted/In Press date: 28 May 2021
e-pub ahead of print date: 6 December 2021
Additional Information: Publisher Copyright: © 2021 Thomas Telford Ltd.
Keywords: bearing capacity, failure, failure envelopes, footings/foundations, probabilistic analysis, random finite element, shallow foundations, soil spatial variability, sparse polynomial chaos expansion/global sensitivity analysis, spatial variability

Identifiers

Local EPrints ID: 452615
URI: http://eprints.soton.ac.uk/id/eprint/452615
ISSN: 0016-8505
PURE UUID: 7a600c6a-2096-40db-8cf7-2459ca0080f4
ORCID for Susan Gourvenec: ORCID iD orcid.org/0000-0002-2628-7914

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Date deposited: 11 Dec 2021 11:29
Last modified: 17 Mar 2024 06:55

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Contributors

Author: Susan Gourvenec ORCID iD
Author: Zhichao Shen
Author: Qiujing Pan
Author: Siau Chen Chian
Author: Yinghui Tian

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