Cyclic Behavior of Clays in Undrained Simple Shear

Azzouz, Amr S.; Malek, Azziz M.; Baligh, Mohsen M.

doi:10.1061/(asce)0733-9410(1989)115:5(637)

Cited by 53 publications

(21 citation statements)

References 9 publications

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“…2.5; As a result they show certain strength loss or failure with increasing number of loading cycles. Sangrey et al (1969), Mitchell and King (1976), Azzouz et al (1989), Zergoun and Vaid (1994) and various others showed that a rapid increase in pore water pressure and a resulting effective stress loss occurs during the initial loading cycles and shear failure occurs if or when the effective stress path touches the monotonic effective stress failure envelope of that clay. However, complete loss of strength or true liquefaction such as in saturated loose sands is generally not a possibility (e.g.…”

Section: Cyclic Shear Strength Claymentioning

confidence: 99%

“…2.4 due to significant reduction in the (secant) shear modulus or stiffness (Vucetic & Dobry, 1991). This cyclic strain is accompanied with or without increasing permanent or average shear strain (Kodaka et al, 2010;Azzouz et al, 1989). Large cyclic strains and accompanied strength loss is a matter of concern for engineers especially in earthquake response analysis.…”

Section: Cyclic Shear Strength Claymentioning

confidence: 99%

“…Over consolidation ratio (OCR) seems to have similar effects on cyclic stress strain behaviour of clays, as it does in monotonic behaviour. For example, Azzouz et al (1989) reported that NC clays produced positive pore water pressure and shifted the stress path gradually towards origin during cyclic shearing. On the other hand, OC clays developed negative pore water pressure at the initial stages.…”

Section: Over Consolidation Ratio (Ocr)mentioning

confidence: 99%

“…Different observations have been reported in literature regarding the effect of OCR on cyclic strength. Azzouz et al (1989) claimed that OC clays showed equal or stronger behaviour than that of NC clays under equal cyclic stress amplitudes. However, Anderson et al (1988) found number of cycles to failure is little bit lower in OC clays than that of NC clays.…”

Section: Over Consolidation Ratio (Ocr)mentioning

confidence: 99%

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Behaviour of sensitive Leda clay under simple shear loading

Theenathayarl¹

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An experimental investigation was conducted on undisturbed sensitive Leda clay samples from the Ottawa area using a simple shear device. Both small strain and large strain tests were conducted under a range of consolidation stress levels. The Carleton University simple shear device was improved to measure shear properties at small strain amplitudes.Strength tests at large strain levels were performed in order to study the monotonic and cyclic behaviour of sensitive Leda clays, while quasi-cyclic tests were carried out to obtain material specific modulus and damping curves at small strain amplitudes.Strength tests indicate that Leda clay might reach a steady state during monotonic loading. Under cyclic loading, the clay deformed with progressively increasing cyclic strain, and liquefaction becomes a concern when cyclic stress amplitudes exceed at least 60% of their monotonic undrained shear strength. Few small amplitude stress or strain cycles do not produce significant strength loss or do not change the subsequent shear behaviour.Successful application of small strain quasi cyclic tests proved to be an optimum means of obtaining modulus reduction and damping data in the laboratory. Material specific modulus reduction and damping ratio curves are presented for Ottawa area Leda clay based on this experimental data. These results show that the behaviour of sensitive clays cannot be simply equated to that of typical non sensitive clays with high plasticity index, if accurate site response analysis results are required.ii

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Section: Cyclic Shear Strength Claymentioning

confidence: 99%

Section: Cyclic Shear Strength Claymentioning

confidence: 99%

Section: Over Consolidation Ratio (Ocr)mentioning

confidence: 99%

Section: Over Consolidation Ratio (Ocr)mentioning

confidence: 99%

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Behaviour of sensitive Leda clay under simple shear loading

Theenathayarl¹

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“…However, recent advances made in this area allow us to better understand the behavior of fine-grained soils during earthquakes. The effects of such factors as shear stress and frequency (Ansal and Erken 1989), the overconsolidation ratio (Azzouz et al 1989), and static shear stress (Lefebvre and Pfendler 1996) are relatively well-studied. Nevertheless, there remain some aspects concerning the properties of fine-grained soils that need to be clarified.…”

Section: Introductionmentioning

confidence: 99%

Undrained cyclic behavior of bentonite–sand mixtures and factors affecting it

et al. 2006

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In this work, the cyclic behavior of bentonite-sand mixtures and factors affecting it were studied by means of a ring-shear apparatus and a scanning electron microscope. It was found that bentonite content had a significant influence on the liquefaction potential of the studied soils. A small amount of bentonite in the mixtures would cause the formation of ''loose'' microstructures, resulting in the occurrence of rapid liquefaction under cyclic loading, while a high bentonite content would cause the formation of clay matrixes, thus raising the soil resistance to liquefaction. In addition, the effect of pore water chemistry on the cyclic behavior of a high plasticity bentonite-sand mixture was carefully examined. It was also found that the presence of ions in pore water would change the clay microfabric, making it more open and thus more vulnerable to liquefaction. Finally, the effects of loading frequency on the cyclic behavior of mixtures with different amounts of bentonite were investigated. It was found that as the bentonite content increased, the influence became more pronounced.

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