Dilatancy Relation for Overconsolidated Clay

Gao, Zhiwei; Zhao, Jidong; Yin, Zhen‐Yu

doi:10.1061/(asce)gm.1943-5622.0000793

Cited by 34 publications

(19 citation statements)

References 46 publications

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“…Similar approach has also been undertaken by previous studies, who defined a separate dilatancy relation based on experimental observations. It is noteworthy that such inconsistency of dilatancy could be caused by the dissipation function we used in Equation and deserves more investigation in the future study.…”

Section: Elastoplastic Modelingmentioning

confidence: 90%

A bounding surface model for anisotropically overconsolidated clay incorporating thermodynamics admissible rotational hardening rule

Chen

Yang

2019

Num Anal Meth Geomechanics

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Summary A bounding surface model is formulated to simulate the behavior of clays that are subject to an anisotropic consolidation stress history. Conventional rotational hardening is revisited from the perspective of thermodynamics. As the free energy cannot be accumulated infinitely upon critical state failure, the deviatoric back stress must vanish. This requires the rotated yield surface to be turned back to eventually align on the hydrostatic axis in the stress plane. Noting that most of the previous propositions violate this restriction, an innovative rotational hardening rule is formulated that is thermodynamically admissible. The bounding surface framework that employs the modified yield surface is applied to simulate elastoplastic deformations for overconsolidated clays, with which the overprediction of strength on the “dry” side can be greatly improved with reasonable results. Other important features, including contractive or dilative response and hardening or softening behavior, can also be well‐captured. It has been shown that the model can simulate three types of reconstituted clays that are sheared with initial conditions over a wide range of anisotropic consolidation stress ratios and overconsolidation ratios under both triaxial undrained and drained conditions. Limitations and potential improvement of the model regarding the fabric anisotropy at critical state have been discussed.

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Section: Elastoplastic Modelingmentioning

confidence: 90%

A bounding surface model for anisotropically overconsolidated clay incorporating thermodynamics admissible rotational hardening rule

Chen

Yang

2019

Num Anal Meth Geomechanics

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“…This can cause extra volume contraction of the saturated matrix, which is similar to the effect of bubble flooding. For the three gassy clays used in this paper, such effect is small because of the extremely low solubility of typical types of biogas; (c) the effect of gas bubbles on yield surface shape (eg,) and dilatancy relationship should be considered to get better prediction of the effective stress paths in undrained triaxial compression.…”

Section: Discussionmentioning

confidence: 99%

Constitutive modelling of fine‐grained gassy soil: A composite approach

Gao

Hong

Wang

2020

Num Anal Meth Geomechanics

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Fine-grained marine sediments containing large undissolved gas bubbles are widely distributed around the world. Presence of the bubbles could degrade the undrained shear strength (s u ) of the soil, when the gas pressure u g is relatively high as compared with the effective stress in the saturated soil matrix. Meanwhile, the addition of bubbles may also increase s u when the difference between u g and pore water pressure u w becomes smaller than the water entry value, causing partial water drainage from the saturated matrix into the bubbles (bubble flooding) during globally undrained shearing. A new constitutive model for describing the two competing effects on the stress-strain relationship of fine-grained gassy soil is proposed within the framework of critical state soil mechanics. The gassy soil is considered as a three-phase composite material with compressible cavities, which allows water entry from the saturated matrix. Bubble flooding is modelled by introducing an additional positive volumetric strain increment of the saturated clay matrix, which is dependent on the difference between pore gas and pore water pressure based on experimental observations. A modified hardening law based on that of the modified Cam clay model is employed, which in conjunction with the expression for bubble flooding, can describe both the detrimental and beneficial effects of gas bubbles on soil strength and plastic hardening in shear. Only two extra parameters in addition to those in the modified Cam clay model are used. It is shown that the key features of the stress-strain relationship of three fine-grained gassy soils can be reproduced satisfactorily. K E Y W O R D Sclays, constitutive relations, offshore engineering, partial saturation, pore pressures, shear strength

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“…All the model parameters for Jingyang loess are summarized in Table 2. It is noticed that some advanced methods for parameter identification have been developed (Jin et al, 2020;Yin et al, 2017Yin et al, , 2016. For practical applications, these methods can make the parameter determination more efficient.…”

Section: Determination Of Parameters M a And Bmentioning

confidence: 99%

“…For all the confining pressures, the model tends to overestimate the amount of volumetric contraction. Better model prediction can be achieved by using an improved yield function that is able to produce variable shapes of yield surfaces (Gao et al, 2017;Yao et al, 2012). The measured and predicted e À logr v curves of oedometer tests for the undisturbed and the remolded specimens are compared in Figure 16.…”

Section: Model Validationmentioning

confidence: 99%

Destructuration of saturated natural loess: From experiments to constitutive modeling

Fu¹,

Gao

Hong

et al. 2020

International Journal of Damage Mechanics

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It has been well recognized that unsaturated natural loess shows significant volume contraction upon wetting due to its metastable internal structure. But the structural effect on stress–strain relationship of saturated natural (undisturbed) loess is much less explored. Few attempts have been made in proposing a constitutive model for saturated natural loess. This study presents both laboratory tests and constitutive modeling of a saturated natural loess, with special focus on the structural effect and evolution of structure damage during loading. Oedometer and drained triaxial compression tests have been carried out on undisturbed and remolded saturated loess samples. It is found that the natural soil structure has dramatic influence on mechanical behavior of loess, including the compressibility, dilatancy, and shear strength. Destructuration, which is the damage of soil structure with deformation, is observed in both oedometer and triaxial tests. A constitutive model is proposed for saturated loess based on the experimental observations. The model is established within the theoretical framework of subloading and superloading surface concepts. Destructuration of loess is assumed to be affected by both plastic volumetric and shear strain. A new method for determining the initial degree of structure is proposed. The model can reasonably predict the compression and shear behavior of both undisturbed and remolded saturated loess.

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Dilatancy Relation for Overconsolidated Clay

Cited by 34 publications

References 46 publications

A bounding surface model for anisotropically overconsolidated clay incorporating thermodynamics admissible rotational hardening rule

A bounding surface model for anisotropically overconsolidated clay incorporating thermodynamics admissible rotational hardening rule

Constitutive modelling of fine‐grained gassy soil: A composite approach

Destructuration of saturated natural loess: From experiments to constitutive modeling

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