Cyclic Secant Shear Modulus and Pore Water Pressure Change in Sands at Small Cyclic Strains

Vučetić, Mladen; Thangavel, Harish; Mortezaie, Ahmadreza

doi:10.1061/(asce)gt.1943-5606.0002490

Cited by 9 publications

(4 citation statements)

References 8 publications

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“…Seed and Idriss [80] and Darendeli [81]. Figure 9 presents the degradation index, δ, with respect to the number of loading cycles N. The results show phenomena similar to those documented by Vucetic and Mortezaie [48] and Vucetic et al [82]. In Figure 9d, loading axial strains of 0.067% and 0.1333% are missing due to specimen failure at a shear-loading frequency of 0.2 Hz and a confining stress of 10 kPa.…”

Section: Undrained Cyclic Triaxial Test Resultssupporting

confidence: 70%

“…After reaching that value, degradation drops rapidly with the number of cycles. This phenomenon is well-documented behaviour for sand in cyclic simple-shear devices [48,82]. To examine the correlation between the degradation index and pore water pressure, the degradation index was plotted against the normalized pore water pressure ratio (Figure 10) for various effective stresses and loading frequencies.…”

Section: Discussionmentioning

confidence: 70%

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Cyclic Behaviour of Uniform Sand in Drained and Undrained Conditions at Low Confining Stress in Small-Scale Landslide Model

Jagodnik

Arbanas

2022

Sustainability

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Earthquakes are one of the main landslide-triggering factors. Earthquakes induce cyclic shear stresses and strains in soil and raise pore water pressure, degrading soil strength towards slope failure. Slopes on which shallow landslides can form due to geological conditions are most susceptible to such failures, mainly because of low confining stress. Effective confining stress has a significant role on soil response during static and cyclic loading. Under low confining stress, soil exhibits dilatant behaviour and can degrade rapidly under cyclic loading. This paper presents the results of undrained and drained cyclic triaxial tests on uniform sandy soil material used for modelling small-scale shallow landslides under 1g conditions. Based on the scaling laws for a model in 1g conditions, the frequencies of straining amplitudes for strain-controlled cyclic triaxial tests were defined. Undrained and drained cyclic triaxial tests on the type of sand used in small-scale landslide models were performed. The sandy samples had been previously consolidated at low confining stress corresponding to the values present in the shallow landslides used as the prototype. The influences of loading frequency and low confining stress on sand behaviour were investigated, and simple models for pore pressure build-up and volumetric strain on sand behaviour were proposed. These simple models can be used to estimate increasing pore water pressure and volumetric strain due to cyclic loading at low confining stress for frequencies lower than 1 Hz. The proposed models show good correlation with the data obtained in the laboratory test.

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Section: Undrained Cyclic Triaxial Test Resultssupporting

confidence: 70%

Section: Discussionmentioning

confidence: 70%

Cyclic Behaviour of Uniform Sand in Drained and Undrained Conditions at Low Confining Stress in Small-Scale Landslide Model

Jagodnik

Arbanas

2022

Sustainability

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“…Figure 16 shows the recent results of tests equivalent to those presented in Figure 10, but conducted on saturated sand instead of clay. They reveal that at the cyclic shear strain amplitudes, g c , between 0.01 % and 0.10 to 0.15 % the secant shear modulus at cycle N, G SN , first increases with N, for up to 10 % of the initial G S1 , and then decreases, while the cyclic pore water pressure, Du N , monotonically increases, and that Du N can actually reach up to 40 % of the initial effective vertical stress before G SN drops below G S1 and sands start to truly degrade [24,27,28,29]. They also demonstrate that the effective stress principle, to the extent that it stipulates that if the pore water pressure increases during cyclic loading and the effective stress decreases, the sand stiffness and strength must decrease, is not universally valid.…”

Section: Threshold Strains For Cyclic Degradation and Pore Water Pres...mentioning

confidence: 99%

Review of Cyclic Soil Behavior and Input Parameters for Seismic Site Response Analyses and Liquefaction

Vučetić¹

2021

1st Croatian Conference on Earthquake Engineering

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During earthquakes soil deposits are exposed to all kinds of seismic waves and are consequently subjected to three-directional cyclic loading and straining. In the geotechnical earthquake engineering practice, however, the analyses of such complex response of the deposits to seismic forces, the site response analyses, are typically reduced to the analyses of the effects of the vertically propagating plane shear waves through horizontally layered deposits. The popular geotechnical laboratory tests for simulation of such behavior are cyclic simple shear, cyclic triaxial, cyclic torsional and resonant column tests that all cyclically shear the soil specimen in just one direction, typically in series of cycles with constant amplitude of shear stress, t c , or shear strain, g c . The paper presents several fundamental aspects of the cyclic soil behavior obtained relatively recently in the cyclic simple shear tests, indicating that the basic research of cyclic and dynamic soil properties is still going on. The parameters and curves derived from cyclic simple shear tests that are used in popular computer models for site response analyses that are treated in this paper include: maximum shear modulus, G max , cyclic secant shear modulus, Gs, equivalent viscous damping ratio, l, curve of the reduction of the first cycle G s with g c , second cycle l versus g c curve, pore water pressure change with the number of cycles N in saturated soils, change of Gs with N, and the cyclic threshold shear strains for pore water pressure change, g tp , and cyclic degradation, g td .

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“…Many experimental studies have been performed on g tp or g td of saturated sands (Dobry et al, 1982;Chen et al, 2019;Vucetic et al, 2021;Saathoff and Achmus, 2022) and terrestrial clays (Ohara and Matsuda, 1988;Hsu and Vucetic, 2004;Hsu and Vucetic, 2006;Mortezaie and Vucetic, 2016;Soralump and Prasomsri, 2016;Ichii and Mikami, 2018;Parsa et al, 2022) by conducting cyclic triaxial tests (CTX), cyclic hollow cylinder torsional shear tests (CHCTS), and cyclic direct simple shear tests (CDSS), and the values of g tp and g td are listed in Table 1. The results of these studies reveal that the values of g tp and g td of a given saturated sand are almost the same, while g tp is larger than g td in a given saturated terrestrial clay.…”

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confidence: 99%

Cyclic threshold shear strain for pore water pressure generation and stiffness degradation in marine clays at Yangtze estuary

et al. 2023

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Cyclic threshold shear strain is a fundamental property of saturated soils under cyclic loading. To investigate the cyclic threshold shear strain for pore water pressure generation (γtp) and stiffness degradation (γtd), a series of strain-controlled multistage undrained cyclic triaxial tests were carried out on in-situ saturated marine clay in the Yangtze estuary with different plasticity index Ip. The test results show that both γtp and γtd increase with increasing Ip, and γtp is larger than γtd for the same marine clay tested under the same conditions, with γtp = 0.017 ~ 0.019%, γtd = 0.008 ~ 0.012% for Ip of 17, γtp = 0.033 ~ 0.039%, γtd = 0.020 ~ 0.025% for Ip of 32, and γtp = 0.040 ~ 0.048%, γtd = 0.031 ~ 0.036% for Ip of 40. Moreover, the development of stiffness degradation may not necessarily require the generation of pore water pressure but can be aggravated by it. Furthermore, the γtp and γtd of marine clay are compared with terrestrial soils and marine clays cited from the published literature, the results indicate that the special marine sedimentary environment and the combined action of flow and tidal wave system cause the γtp and γtd of marine clay in the Yangtze estuary to be smaller than that of the terrestrial clays and marine clays in other sea areas.

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Cyclic Secant Shear Modulus and Pore Water Pressure Change in Sands at Small Cyclic Strains

Cited by 9 publications

References 8 publications

Cyclic Behaviour of Uniform Sand in Drained and Undrained Conditions at Low Confining Stress in Small-Scale Landslide Model

Cyclic Behaviour of Uniform Sand in Drained and Undrained Conditions at Low Confining Stress in Small-Scale Landslide Model

Review of Cyclic Soil Behavior and Input Parameters for Seismic Site Response Analyses and Liquefaction

Cyclic threshold shear strain for pore water pressure generation and stiffness degradation in marine clays at Yangtze estuary

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