Damping of Sands for Varying Saturation

Madhusudhan, B. N.; Kumar, Jyant

doi:10.1061/(asce)gt.1943-5606.0000895

Cited by 30 publications

(7 citation statements)

References 21 publications

(28 reference statements)

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“…These observations were attributed primarily to the additional viscous damping component in moist and saturated samples which increased material damping in comparison with the dry specimens. These results are in qualitative agreement with the observed response of pure sands, for example the research work by Madhusudhan and Kumar (2013). In their study, the effect of the degree of saturation on material damping of a quartz sand was investigated.…”

Section: Small-strain Materials Dampingsupporting

confidence: 88%

Effects of state of test sample, specimen geometry and sample preparation on dynamic properties of rubber–sand mixtures

Senetakis

Anastasiadis

2015

Geosynthetics International

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The study presents resonant column test results on sand mixed with granulated rubber. The experiments were carried out on samples within a range of rubber content from 0 to 15% by dry weight of sand-rubber mixtures, at variable isotropic effective stresses, p′, state of test sample and sample preparation method. Both small-diameter specimens of 36 mm × 82 mm in size and large-diameter samples of about 70 mm × 140 mm in size were tested in torsional mode of vibration at very small shear strain amplitudes, in general less than 10 −5. Specimens were tested in a dry state, a moist state with a very small water content inclusion and a fully saturated state. The data indicated that for a given p′, the increase of rubber content shifted the obtained resonant frequencies to lower values, the small-strain shear modulus, G 0 , decreased, whereas small-strain material damping, D s0 , increased. The state of test sample, namely dry, moist or fully saturated, did not affect the obtained small-strain shear modulus values but did affect the obtained D s0. G 0 could efficiently be described through typical formulas of G 0 against p′ used for sands, by treating the volume of rubber particles as part of the total volume of voids into the void ratio function of the G 0-p′ relationship. By preparing the samples at variable initial void ratios, comparisons could be obtained between samples of variable rubber contents and state of test sample but at a given resonant frequency. This is very important in capturing the behaviour of the mixtures in resonant column test which is a non-frequency-controlled method and thus the effect of rubber content and loading frequency could be de-coupled in the experiments.

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Section: Small-strain Materials Dampingsupporting

confidence: 88%

Effects of state of test sample, specimen geometry and sample preparation on dynamic properties of rubber–sand mixtures

Senetakis

Anastasiadis

2015

Geosynthetics International

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“…However, a few studies have been carried out in the literature on the material damping of granular soils in the presence of inter-particle water. 86 As expected theoretically and also truly confirmed by the negative power of ′ in a mathematical sense, the soil damping is considerably higher in magnitude close to the ground surface and decreases abruptly with depth. This reduction along depth continues insofar as the damping ratio reaches fairly constant magnitudes.…”

Section: Soil Materials Dampingsupporting

confidence: 71%

Lower bound analysis of modified pseudo‐dynamic lateral earth pressures for retaining wall‐backfill system with depth‐varying damping using FEM‐Second order cone programming

Fathipour

Payan

Chenari

et al. 2021

Num Anal Meth Geomechanics

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Realistic constitutive ground models are critical in the evaluation of soilstructure interaction problems and the assessment of key design parameters in the seismic analysis of infrastructure systems. In the present study, the modified pseudo-dynamic lateral earth pressures acting on retaining structure with granular backfill of depth-varying damping ratio are evaluated adopting the lower bound limit analysis in conjunction with the finite element (FE) discretization method using second-order cone programming (SOCP). The earthquake loading is simulated by the propagation of shear and primary waves through nonconstant inertia forces in the horizontal and vertical directions, respectively. The influence of varying damping ratio alongside the retaining wall height on the seismic active and passive lateral earth pressures is effectively taken into account by adopting well-established formulas published in the literature. It is shown that failing to consider the damping variation with depth while performing the modified pseudo-dynamic analysis could lead to precarious, unrealistic estimates of design parameters. K E Y W O R D Sfinite element limit analysis (FELA), lateral earth pressure, lower bound, material damping, modified pseudo-dynamic method, second-order cone programming (SOCP)

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“…This difference is attributed to the saturation of liquefiable sands. 57 As for structures, a similar increase is N (final) Chi-chi 1.0 g Scaled to PGA = 1.0 g, 0~60 s / / / / Note: PGA = peak ground acceleration, PGV = peak ground velocity, AI = arias intensity, HI = Housner intensity observed, from 5.38% for nonliquefiable sands to 8.43% for liquefiable sands (increased by 57%). These damping ratios serve as complements to references of damping ratios for future numerical simulations of soil-structure systems.…”

Section: Frequency and Damping Of The Soil-bridge Systemmentioning

confidence: 67%

Shake‐table investigation of scoured RC pile‐group‐supported bridges in liquefiable and nonliquefiable soils

Wang

Shang

2019

Earthq Engng Struct Dyn

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Summary This paper presents results of one‐g shake‐table tests on scoured pile‐group‐supported bridge models in saturated (liquefiable) and dry (nonliquefiable) sands. The primary objective is to reveal the influence of liquefaction on seismic demands and failure mechanism of scoured bridges. To this end, two identical models, each consisting of a 2 × 2 reinforced concrete pile‐group with a center‐to‐center spacing of 3 times pile diameter, a cap and a single pier with a lumped iron block, were constructed and embedded into saturated and dry sands, respectively, with the same scour depth of 4 times pile diameter. Typical test results, including excess pore pressure, acceleration and displacement demands are interpreted first, followed by the focus on curvature demands and associated seismic failure mechanism identification. Finally, inertial and kinematic effects on pile curvature demands are estimated using cross‐correlation analyses. Results show that near‐pile liquefied soils exhibit more remarkable dilation tendency as compared to far field. For bridges under the given scour depth, soil liquefaction tends to significantly affect the failure modes via transferring damage positions from pier bottom to pile head and meanwhile from underground pile to pile head. In addition, pile group effects appear to be significant in nonliquefiable soils while to be relatively inessential in liquefied soils. Moreover, the inertial effect is more prominent in nonliquefiable soils, while the kinematic effect itself generally appears to be more significant in liquefiable soils. The test results can be used to validate numerical models for future studies.

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Damping of Sands for Varying Saturation

Cited by 30 publications

References 21 publications

Effects of state of test sample, specimen geometry and sample preparation on dynamic properties of rubber–sand mixtures

Effects of state of test sample, specimen geometry and sample preparation on dynamic properties of rubber–sand mixtures

Lower bound analysis of modified pseudo‐dynamic lateral earth pressures for retaining wall‐backfill system with depth‐varying damping using FEM‐Second order cone programming

Shake‐table investigation of scoured RC pile‐group‐supported bridges in liquefiable and nonliquefiable soils

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