Flexural excitation in a standard torsional-resonant column device

Cascante, Giovanni; Santamarina, J. Carlos; Yassir, Najwa

doi:10.1139/cgj-35-3-478

Cited by 18 publications

(42 citation statements)

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“…(3) Assume a certain value of E s ; the initial assumed value of E s can be taken on the lower side from the method of Cascante et al (1998). From the measured value of u m associated with the fundamental mode of vibration, determine the value of the parameter A as defined in eq.…”

Section: Solution Proceduresmentioning

confidence: 99%

“…After obtaining the solution, following the steps similar to those used by Cascante et al (1998), the average axial strain, 3 av , in the entire sample on either side (tensioncompression) of the neutral axis can be shown to be given by the following expression:…”

Section: Average Axial Strain In the Samplementioning

confidence: 99%

“…Most of the available data on resonant column tests is for the torsion mode; the available literature on the flexure mode is rather limited. The methodology of Cascante et al (1998) is often used to find the elastic modulus of the sample from measurement of the resonant frequency in the flexure mode; this method is also briefly outlined in Cascante and Santamarina (1997). In this method, the mode shape of the horizontal displacement of the sample is assumed to be a third order polynomial and, in addition, the value of the bending moment at the top of the sample is taken equal to zero.…”

Section: Introductionmentioning

confidence: 99%

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On determining the elastic modulus of a cylindrical sample subjected to flexural excitation in a resonant column apparatus

Kumar

Madhusudhan

2010

Can. Geotech. J.

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For resonant column tests conducted in the flexure mode of excitation, a new methodology has been proposed to find the elastic modulus and associated axial strain of a cylindrical sample. The proposed method is an improvement over the existing one, and it does not require the assumption of either the mode shape or zero bending moment condition at the top of the sample. A stepwise procedure is given to perform the necessary calculations. From a number of resonant column experiments on aluminum bars and dry sand samples, it has been observed that the present method as compared with the one available in literature provides approximately (i) 5.9%-7.3% higher values of the elastic modulus and (ii) 6.5%-7.3% higher values of the associated axial strains.Résumé : Une nouvelle méthodologie est proposée pour déterminer le module élastique et les déformations axiales associées pour un échantillon cylindrique, à l'aide d'essais en colonne de résonance effectués dans le mode d'excitation en flexion. La méthode proposée améliore la méthode existante puisqu'elle ne nécessite pas la supposition de la forme du mode ni de la condition zéro du moment de torsion dans le haut de l'échantillon. Une procédure étape-par-étape est présentée afin d'effectuer les calculs nécessaires. Dans le cas de plusieurs essais en colonne de résonance sur des barres d'aluminium et des échantillons de sable sec, la méthode proposée comparativement à la méthode de la littérature offre approximativement (i) des valeurs du module élastique supérieures de 5,9% à 7,3%, et (ii) des valeurs des déformations axiales associées supérieures de 6,5% à 7,3%.

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Section: Solution Proceduresmentioning

confidence: 99%

Section: Average Axial Strain In the Samplementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On determining the elastic modulus of a cylindrical sample subjected to flexural excitation in a resonant column apparatus

Kumar

Madhusudhan

2010

Can. Geotech. J.

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“…In this apparatus, the bottom of the specimen is fixed to the pedestal while the top surface is left free. These resonant column apparatus were previously used to perform the tests only in torsional mode until it was demonstrated by Cascante et al (1998) to perform the tests in flexural mode. In the present study, the tests were performed using a fixed-free type resonant column apparatus.…”

Section: Resonant Column Testmentioning

confidence: 99%

“…Cascante et al (1998) gave the circular resonant frequency for a soil specimen of length L by using Rayleigh's method and considering N distributed mass m i as:…”

Section: Determination Of Poisson's Ratio Mmentioning

confidence: 99%

Influence of Shear Strain on the Poisson’s Ratio of Clean Sands

Dutta

Saride

2016

Geotech Geol Eng

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In the present study, a series of resonant column tests was performed to determine the influence of confining pressure, shear strain and relative density on the dynamic properties and Poisson's ratio of poorly graded clean sand. The tests were performed on the sand specimens of size 50 9 100 mm compacted at relative densities 30, 50 and 75 %. To achieve the corresponding relative density, sand was compacted in 5 equal layers with a specific number of blows. A fixed-free type resonant column apparatus was used to determine the dynamic soil properties at various confining pressures. It has been inferred from the data that the shear modulus (G) increases with an increase in confining pressure and relative density; and decreases with an increase in shear strain. In addition, damping ratio (D) decreases with an increase in confining pressure and relative density; and increases with an increase in shear strain. In addition, Poisson's ratio (m) decreases with an increase in confining pressure and relative density and increases with an increase in the shear strain. The variation of shear modulus with Poisson's ratio is also discussed. It has been found that there has been a decrease in shear modulus with an increase in Poisson's ratio of the soil. It is noticed that the small strain shear modulus determined from the present study closely matches with the value determined using the correlations from the literature.

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Measurements of the changing wave velocities of sand during the formation and dissociation of disseminated methane hydrate

2015

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The formation and dissociation of methane hydrate within sediment can lead to large changes in wave velocities, which provide valuable insights into the processes involved in hydrate formation. These are of practical importance in geophysical characterization, as well as developing strategies for the future exploitation of methane hydrates. This paper presents changes in wave velocity, measured during hydrate formation, and subsequent dissociation, using the resonant column apparatus. Hydrate was formed under "drained" and "undrained" conditions. Drained specimens had free access to methane during formation, while for undrained specimens, methane content was fixed. Hydrate formation and dissociation were induced by changing the specimen temperature under constant effective stress. In excess of 20 determinations of shear wave and flexural wave velocity were carried out over a 9 h period, both during hydrate formation and dissociation. This time was sufficient to record almost all of the changes in wave velocity within a specimen. The exothermic nature of hydrate formation was clearly seen in the form of spikes in temperature measured at the base of the specimens. For all specimens, the relationship between wave velocity and degree of hydrate saturation was nonlinear and significantly different during formation and dissociation. The patterns observed suggest that hydrate morphology not only is important in controlling the ultimate wave velocities, at the end of formation, but has a significant impact on the rates of change of wave velocities during formation and dissociation. A conceptual model is presented to explain differences in observed behavior during formation and dissociation.

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Flexural excitation in a standard torsional-resonant column device

Cited by 18 publications

References 0 publications

On determining the elastic modulus of a cylindrical sample subjected to flexural excitation in a resonant column apparatus

On determining the elastic modulus of a cylindrical sample subjected to flexural excitation in a resonant column apparatus

Influence of Shear Strain on the Poisson’s Ratio of Clean Sands

Measurements of the changing wave velocities of sand during the formation and dissociation of disseminated methane hydrate

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