Pre-failure strain softening and pre-failure instability of sand: a comparative study

Chu, Jian; Leong, W K

doi:10.1680/geot.51.4.311.39402

Cited by 34 publications

(32 citation statements)

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“…For the loose sample (e0 = 0.6491), it initially contracts towards 246 the critical state line after the onset of instability, and crosses the CSL followed by dilation before 247 collapsing. Similar observations in the e-p' plane from laboratory CSD tests have been reported by 248 Chu and Leong (2001). 249 between the initial void ratio before shearing takes place (e0) and the void ratio at the critical state (ecs) 252 at the same p'.…”

supporting

confidence: 81%

Exploring the micro-mechanics of triaxial instability in granular materials

et al. 2016

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14The instability of granular materials due to water infiltration under fully drained conditions has been 15 previously considered in experimental studies. While laboratory experiments can provide macro-scale 16 insight into drained instability, the micro-mechanics under such conditions are yet to be explored. 17This study has employed the Discrete Element Method (DEM) to simulate constant shear drained 18 (CSD) tests for an ideal soil. CSD tests were initiated from a range of packing densities and stress 19 conditions. The DEM simulations were able to qualitatively replicate laboratory CSD tests. The 20 choice of the loading control parameter was seen to play a central role in the macro-scale second-21 order work to identify an effective failure. All samples considered attained an onset of instability that 22 coincided with fluctuations in the second-order work from a particle scale. The time of occurrence of 23 the onset of instability was seen to depend on initial packing density and stress state. A change in the 24 evolution of macro-and micro-mechanical quantities, showing either a sharp increase or decrease, 25 was observed once the CSD conditions had been reached. Finally, conventional drained then constant 26 volume (CDCV) tests were carried out where the appearance of instabilities and the evolution of 27 macro and micro quantities were found to be different from those observed in CSD tests. The results 28 presented in this study indicate that the constant shear drained loading conditions can result in more 29 unfavourable situations than for undrained loading condition. 30Keywords: Discrete-element modelling; fabric/structure of soils; particle-scale behaviour 31 32

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confidence: 81%

Exploring the micro-mechanics of triaxial instability in granular materials

et al. 2016

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“…This conclusion is consistent with that of Chu and Leong (2001). On the other hand, instability may occur without strain softening, indicating that the occurrence of strain softening is not a necessary condition for instability.…”

Section: W＝0supporting

confidence: 90%

“…To be clear and precise, material instability in this paper is referred to as non-positive second order work (i.e., d 2 WÃ0), while strain softening is used to denote a decrease in the shear resistance of a material, with failure being the state at which the maximum friction angle is mobilized; i.e., f＝ fpeak. In the context of conventional triaxial stress, two types of strain softening might be observed (Chu and Leong, 2001). One is a reduction of deviator stress (i.e., dqº0) with continuous straining, which is referred to as deviatoric softening.…”

Section: Introductionmentioning

confidence: 99%

Effect of Dilatancy on Instability, Pre-Instability Strain Softening of Sand Along Proportional Strain Paths

Guo

2007

Soils and Foundations

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“…other than undrained) conditions (Chu et al, 1993;Chu & Leong, 2001). Failure mechanisms related to a redistribution of void ratio within a globally undrained sand layer ( Fig.…”

Section: Other Concernsmentioning

confidence: 99%

Difficulties in the determination of post-liquefaction strength for sand

Chu

Wanatowski

2014

Géotechnique Letters

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Article:Chu, J and Wanatowski, D orcid.org/0000-0002-5809-0374 (2014) Difficulties in the determination of post-liquefaction strength for sand. Géotechnique Letters, 4 (1). pp. 57-61.https://doi.org/10.1680/geolett.13.00076 eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request.Difficulties in the determination of post-liquefaction strength for sand J. CHU* and D. WANATOWSKI{ Static liquefaction has been considered one of the commonest failure mechanisms for granular soil slopes or tailings dams. One of the design approaches adopted is based on the so-called postliquefaction strength as a design parameter. However, determination of the post-liquefaction strength by laboratory tests is problematic. In this paper, experimental data are used to illustrate that the postliquefaction strength cannot be determined properly or uniquely in the laboratory. The assumption of an undrained condition is also questionable for sand or tailings with relatively high permeability under static loading conditions. Due to the above deficiencies, it is recommended that engineers stop using the post-liquefaction strength as a design parameter in practice.

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Pre-failure strain softening and pre-failure instability of sand: a comparative study

Cited by 34 publications

References 21 publications

Exploring the micro-mechanics of triaxial instability in granular materials

Exploring the micro-mechanics of triaxial instability in granular materials

Effect of Dilatancy on Instability, Pre-Instability Strain Softening of Sand Along Proportional Strain Paths

Difficulties in the determination of post-liquefaction strength for sand

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