A Comparative Analysis of In Situ Testing Methods for Clay Strength Evaluation Using the Coupled Eulerian–Lagrangian Method

The progression of marine resource exploration into deepwater and ultra-deepwater regions has intensified the requirement for precise quantification of the undrained shear strength of clay. Although diverse in situ testing methodologies—including the vane shear test (VST), cone penetration test (CPT...

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Main Authors: Hebo Wang, Yifa Wang, Biao Li, Wengang Qi, Ning Wang
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Journal of Marine Science and Engineering
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Online Access:https://www.mdpi.com/2077-1312/13/5/935
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author Hebo Wang
Yifa Wang
Biao Li
Wengang Qi
Ning Wang
author_facet Hebo Wang
Yifa Wang
Biao Li
Wengang Qi
Ning Wang
author_sort Hebo Wang
collection DOAJ
description The progression of marine resource exploration into deepwater and ultra-deepwater regions has intensified the requirement for precise quantification of the undrained shear strength of clay. Although diverse in situ testing methodologies—including the vane shear test (VST), cone penetration test (CPT), T-bar penetration test (TPT), and ball penetration test (BPT)—are widely utilized for the assessment of clay strength, systematic discrepancies and correlations between their derived measurements remain inadequately resolved. The aim of this work is to provide a systematic comparison of strength interpretations across different in situ testing methods, with emphasis on identifying method-specific biases under varying soil behaviors. To achieve this, a unified numerical simulation framework was developed to simulate these four prevalent testing techniques, employing large-deformation finite element analysis via the Coupled Eulerian–Lagrangian (CEL) approach. The model integrates critical constitutive behaviors of marine clays, specifically strain softening and strain rate dependency, to replicate in situ shear strength evolution. Rigorous sensitivity analyses confirm the model’s robustness. The results indicate that, when the stain rate and softening effects are neglected, the resistance factors from the CPT and VST remain largely insensitive to shear strength variations. However, T-bar and ball penetrometers tend to underestimate strength by up to 15% in high-strength soils due to the incomplete development of a full-flow failure mechanism. As a result, their application in high-strength soils is not recommended. With both the strain rate and softening effects considered, the interpreted strength value <i>S</i><sub>ut</sub> from the CPT increases by 13.5% compared to cases excluding these effects, while other methods exhibit marginal decreases of 4–5%. The isolated analysis of strain softening reveals that, under identical softening parameters, the CPT demonstrates the least sensitivity to strain softening among the four methods examined, with the factor reduction ratio <i>N<sub>s</sub></i>/<i>N</i><sub>0</sub> ranging from 0.76 to 1.00, while the other three methods range from 0.65 to 0.88. The results indicate that the CPT is well suited for strength testing in soils exhibiting pronounced softening behavior, as it reduces the influence of strain softening on the measured results. These findings provide critical insights into method-specific biases in undrained shear strength assessments, supporting a more reliable interpretation of in situ test data for deepwater geotechnical applications.
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spelling doaj-art-59f1317192154bf596a58bdfe3dc7fbe2025-08-20T02:34:01ZengMDPI AGJournal of Marine Science and Engineering2077-13122025-05-0113593510.3390/jmse13050935A Comparative Analysis of In Situ Testing Methods for Clay Strength Evaluation Using the Coupled Eulerian–Lagrangian MethodHebo Wang0Yifa Wang1Biao Li2Wengang Qi3Ning Wang4Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, ChinaDepartment of Infrastructure Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Melbourne, VIC 3010, AustraliaInstitute of Mechanics, Chinese Academy of Sciences, Beijing 100190, ChinaInstitute of Mechanics, Chinese Academy of Sciences, Beijing 100190, ChinaInstitute of Mechanics, Chinese Academy of Sciences, Beijing 100190, ChinaThe progression of marine resource exploration into deepwater and ultra-deepwater regions has intensified the requirement for precise quantification of the undrained shear strength of clay. Although diverse in situ testing methodologies—including the vane shear test (VST), cone penetration test (CPT), T-bar penetration test (TPT), and ball penetration test (BPT)—are widely utilized for the assessment of clay strength, systematic discrepancies and correlations between their derived measurements remain inadequately resolved. The aim of this work is to provide a systematic comparison of strength interpretations across different in situ testing methods, with emphasis on identifying method-specific biases under varying soil behaviors. To achieve this, a unified numerical simulation framework was developed to simulate these four prevalent testing techniques, employing large-deformation finite element analysis via the Coupled Eulerian–Lagrangian (CEL) approach. The model integrates critical constitutive behaviors of marine clays, specifically strain softening and strain rate dependency, to replicate in situ shear strength evolution. Rigorous sensitivity analyses confirm the model’s robustness. The results indicate that, when the stain rate and softening effects are neglected, the resistance factors from the CPT and VST remain largely insensitive to shear strength variations. However, T-bar and ball penetrometers tend to underestimate strength by up to 15% in high-strength soils due to the incomplete development of a full-flow failure mechanism. As a result, their application in high-strength soils is not recommended. With both the strain rate and softening effects considered, the interpreted strength value <i>S</i><sub>ut</sub> from the CPT increases by 13.5% compared to cases excluding these effects, while other methods exhibit marginal decreases of 4–5%. The isolated analysis of strain softening reveals that, under identical softening parameters, the CPT demonstrates the least sensitivity to strain softening among the four methods examined, with the factor reduction ratio <i>N<sub>s</sub></i>/<i>N</i><sub>0</sub> ranging from 0.76 to 1.00, while the other three methods range from 0.65 to 0.88. The results indicate that the CPT is well suited for strength testing in soils exhibiting pronounced softening behavior, as it reduces the influence of strain softening on the measured results. These findings provide critical insights into method-specific biases in undrained shear strength assessments, supporting a more reliable interpretation of in situ test data for deepwater geotechnical applications.https://www.mdpi.com/2077-1312/13/5/935clayundrained shear strengthstrain softeningstrain rateCEL method
spellingShingle Hebo Wang
Yifa Wang
Biao Li
Wengang Qi
Ning Wang
A Comparative Analysis of In Situ Testing Methods for Clay Strength Evaluation Using the Coupled Eulerian–Lagrangian Method
Journal of Marine Science and Engineering
clay
undrained shear strength
strain softening
strain rate
CEL method
title A Comparative Analysis of In Situ Testing Methods for Clay Strength Evaluation Using the Coupled Eulerian–Lagrangian Method
title_full A Comparative Analysis of In Situ Testing Methods for Clay Strength Evaluation Using the Coupled Eulerian–Lagrangian Method
title_fullStr A Comparative Analysis of In Situ Testing Methods for Clay Strength Evaluation Using the Coupled Eulerian–Lagrangian Method
title_full_unstemmed A Comparative Analysis of In Situ Testing Methods for Clay Strength Evaluation Using the Coupled Eulerian–Lagrangian Method
title_short A Comparative Analysis of In Situ Testing Methods for Clay Strength Evaluation Using the Coupled Eulerian–Lagrangian Method
title_sort comparative analysis of in situ testing methods for clay strength evaluation using the coupled eulerian lagrangian method
topic clay
undrained shear strength
strain softening
strain rate
CEL method
url https://www.mdpi.com/2077-1312/13/5/935
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