The liquefaction of clayey soils under cyclic loading

Gratchev, Ivan; Sassa, Kyoji; Осипов, В. И.; Sokolov, V. N.

doi:10.1016/j.enggeo.2006.04.006

Cited by 106 publications

(54 citation statements)

References 19 publications

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“…Yilmaz et al (2004) reported a significant deformations of the city AdapazariTurkey after 1999 Kocaeli earthquake, where study sites predominately consisted of fine-grained surface soils of low-plastic silt-clay mixtures. Gratchev et al (2006) found that the same relationship between the plasticity index of soil and cyclic stress ratio was obtained for artificial mixtures and natural soils, which suggests usage of plasticity indices (PI) as a criterion for estimating the liquefaction potential of clayey soil. As stated by Boulanger and Idriss (2004) the situation is, however, more complicated for lowplasticity silts and clays over a fairly narrow range of PI that are near the transition between sand-like and clay-like behavior.…”

Section: Introductionmentioning

confidence: 56%

Study on seismic behavior of nonplastic silt by means of ring-shear apparatus

2008

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Study on seismic behavior of nonplastic silt by means of ring-shear apparatusAbstract The influence of static shear stress on undrained cyclic behavior of nonplastic and low-plasticity silts has been studied by means of undrained cyclic torque-controlled ring-shear tests. The cyclic and post-cyclic behavior of silty soils assumed on sliding surface were investigated to assess the liquefaction potential and cyclically induced deformation of silty slopes. Six different initial static shear stresses corresponding to slope angles from 0°to 25°w ere examined. To better understand undrained cyclic behavior of silt governed by a change in clay content, three different mixtures were achieved by mixing of nonplastic silt with 0%, 10%, and 20% of commercially available clay. These tests were conducted to simulate field conditions prior to earthquake with initial static shear stresses corresponding to slopes and those with no initial static shear stresses of level grounds. The gradual loss of mobilized undrained cyclic shear resistance after failure and pore water buildup in relation to a number of cycles was observed. The undrained response of the soil to cyclic shear stress loading with the constant amplitude revealed the significant effect of the initial static shear stress on the excess pore water pressure generation and post-failure shear resistance. Test results showed that an increase in the initial static shear stress at the given initial effective normal stress is associated with an increase of mobilized shear resistance at its peak state; however, the actual resistance to liquefaction diminished for both nonplastic and low-plasticity silts. During both cyclic and post-cyclic stages of loading, distinctly different types of shear deformation were identified. In order to evaluate mobility of landslides, a modified conventional brittleness index for seismic loading, I BS ¼ S peak À S u À Á S peak À S initial À Á , was proposed and used to characterize unlimited deformation of silts.

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Section: Introductionmentioning

confidence: 56%

Study on seismic behavior of nonplastic silt by means of ring-shear apparatus

2008

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“…5a), the clay particles tend to aggregate and accumulate on the surface of sand grains or at the contact points of sand particles, forming a bridge-like structure bonding the grains to each other. Such particle arrangements produce significant pore spaces, Osipov et al (1984) and Gratchev et al (2006b),, who reported that lowstrength ''clay bridges'' at the contact points of sand grains were easily destroyed during cyclic loading, destabilizing the whole structure. It is likely that for B7 the destruction of ''clay bridges'' during cyclic loading was the trigger for rapid liquefaction.…”

Section: The Effects Of Bentonite Content On the Cyclic Behavior Of Bmentioning

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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“…Now, ring shear apparatuses have become essential for soil behavior studies, especially for measuring shear resistance involved in large shear displacement with less ambiguity. Based on ring shear tests, various correlations between residual strengths and soil index properties have been proposed (Lupini et al 1981;Skempton 1985;Gibo et al 1987;Collotta et al 1989;Moore 1991;Di and Fenelli 1994;Stark and Eid 1994;Tika et al 1996;Kamai 1998;Okada et al 2004;Gratchev et al 2006). Together with microstructure analysis of soil, these studies greatly expand people's understanding of the nature of residual strength generation.…”

Section: Introductionmentioning

confidence: 97%

Effect of cyclic loading on the residual strength of over-consolidated silty clay in a ring shear test

Hong

Guo

et al. 2011

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Effect of cyclic loading on the residual strength of over-consolidated silty clay in a ring shear test Abstract In this paper, the effect of cyclic loading on drained residual strength of over-consolidated silty clay is examined based on the results from ring shear tests which were conducted with a sophisticated ring shear apparatus. Initially sheared to form shear zones under different pre-consolidation pressures and at different shear rates (SRs), soil samples were then tested under cyclic loading. After the cyclic loading application, the samples were re-sheared while the corresponding shear strengths were measured. The results show that the effect of cyclic loading on residual strength is noticeable. The effect is related to pre-consolidation history and SR of the soil samples. Under conditions of relatively low over-consolidation ratio (OCR), the soil samples show an increase in residual strength with decreasing SR after cyclic loading. Most of the peak strength values after cyclic loading are higher than the residual strength values obtained before cyclic loading. Two effects of cyclic loading on the residual strength are identified: (a) If OCR is less than or equal to 3.0, the residual strengths measured after cyclic loading are larger than those before cyclic loading; (b) If OCR is greater than or equal to 3.5, the residual strengths after cyclic loading tend to become lower than those in the shear tests before cyclic loading.

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The liquefaction of clayey soils under cyclic loading

Cited by 106 publications

References 19 publications

Study on seismic behavior of nonplastic silt by means of ring-shear apparatus

Study on seismic behavior of nonplastic silt by means of ring-shear apparatus

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

Effect of cyclic loading on the residual strength of over-consolidated silty clay in a ring shear test

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