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Measurement of frequency-dependent dynamic properties of soils using the resonant-column device / Z. H. Khan in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°9 (Septembre 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1319–1326 Titre : Measurement of frequency-dependent dynamic properties of soils using the resonant-column device Type de document : texte imprimé Auteurs : Z. H. Khan, Auteur ; G. Cascante, Auteur ; M. H. El Naggar, Auteur Année de publication : 2008 Article en page(s) : pp. 1319–1326 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Resonance  Velocity  Damping  Soil  dynamics  Soil  properties  Soil  tests Résumé : Dynamic properties of soils are commonly evaluated at resonance; thus, their variation with frequency is difficult to measure. A nonresonance (NR) method has been recently used for testing soils at low frequencies and strain levels below the linear threshold shear strain. However, the NR method has not been validated with the standard resonant method for different shear strain levels. In this study, the NR method is used to measure the dynamic properties of soils at low and midstrain levels for a maximum frequency bandwidth between 5 and 100Hz using the resonant-column device. A new transfer function (NTF) equation is introduced to compare the dynamic properties measured using the NR method and the conventional transfer function approach. Experimental results for two sands and a sand–bentonite–mud mixture are presented for different strain and stress confinement levels. Results from the NR method compare well with the standard resonant column method at the resonant frequency if the strain levels are the same. The NTF approach can be used to measure the dependence of phase velocity of shear waves with frequency. However, the NTF method cannot be used to measure the variation of material damping with frequency. On the other hand, the NR method can be used to measure the degradation curves of wave velocity and material damping ratio as a function of frequency. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2813 [...] [article] Measurement of frequency-dependent dynamic properties of soils using the resonant-column device [texte imprimé] / Z. H. Khan, Auteur ; G. Cascante, Auteur ; M. H. El Naggar, Auteur . - 2008 . - pp. 1319–1326. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1319–1326 Mots-clés : Resonance  Velocity  Damping  Soil  dynamics  Soil  properties  Soil  tests Résumé : Dynamic properties of soils are commonly evaluated at resonance; thus, their variation with frequency is difficult to measure. A nonresonance (NR) method has been recently used for testing soils at low frequencies and strain levels below the linear threshold shear strain. However, the NR method has not been validated with the standard resonant method for different shear strain levels. In this study, the NR method is used to measure the dynamic properties of soils at low and midstrain levels for a maximum frequency bandwidth between 5 and 100Hz using the resonant-column device. A new transfer function (NTF) equation is introduced to compare the dynamic properties measured using the NR method and the conventional transfer function approach. Experimental results for two sands and a sand–bentonite–mud mixture are presented for different strain and stress confinement levels. Results from the NR method compare well with the standard resonant column method at the resonant frequency if the strain levels are the same. The NTF approach can be used to measure the dependence of phase velocity of shear waves with frequency. However, the NTF method cannot be used to measure the variation of material damping with frequency. On the other hand, the NR method can be used to measure the degradation curves of wave velocity and material damping ratio as a function of frequency. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2813 [...]

Measurement of frequency-dependent dynamic properties of soils using the resonant-column device / Z. H. Khan in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°9 (Septembre 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1319–1326 Titre : Measurement of frequency-dependent dynamic properties of soils using the resonant-column device Type de document : texte imprimé Auteurs : Z. H. Khan, Auteur ; G. Cascante, Auteur ; M. H. El Naggar, Auteur Année de publication : 2008 Article en page(s) : pp. 1319–1326 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Resonance  Velocity  Damping  Soil  dynamics  Soil  properties  Soil  tests Résumé : Dynamic properties of soils are commonly evaluated at resonance; thus, their variation with frequency is difficult to measure. A nonresonance (NR) method has been recently used for testing soils at low frequencies and strain levels below the linear threshold shear strain. However, the NR method has not been validated with the standard resonant method for different shear strain levels. In this study, the NR method is used to measure the dynamic properties of soils at low and midstrain levels for a maximum frequency bandwidth between 5 and 100Hz using the resonant-column device. A new transfer function (NTF) equation is introduced to compare the dynamic properties measured using the NR method and the conventional transfer function approach. Experimental results for two sands and a sand–bentonite–mud mixture are presented for different strain and stress confinement levels. Results from the NR method compare well with the standard resonant column method at the resonant frequency if the strain levels are the same. The NTF approach can be used to measure the dependence of phase velocity of shear waves with frequency. However, the NTF method cannot be used to measure the variation of material damping with frequency. On the other hand, the NR method can be used to measure the degradation curves of wave velocity and material damping ratio as a function of frequency. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2813 [...] [article] Measurement of frequency-dependent dynamic properties of soils using the resonant-column device [texte imprimé] / Z. H. Khan, Auteur ; G. Cascante, Auteur ; M. H. El Naggar, Auteur . - 2008 . - pp. 1319–1326. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°9 (Septembre 2008) . - pp. 1319–1326 Mots-clés : Resonance  Velocity  Damping  Soil  dynamics  Soil  properties  Soil  tests Résumé : Dynamic properties of soils are commonly evaluated at resonance; thus, their variation with frequency is difficult to measure. A nonresonance (NR) method has been recently used for testing soils at low frequencies and strain levels below the linear threshold shear strain. However, the NR method has not been validated with the standard resonant method for different shear strain levels. In this study, the NR method is used to measure the dynamic properties of soils at low and midstrain levels for a maximum frequency bandwidth between 5 and 100Hz using the resonant-column device. A new transfer function (NTF) equation is introduced to compare the dynamic properties measured using the NR method and the conventional transfer function approach. Experimental results for two sands and a sand–bentonite–mud mixture are presented for different strain and stress confinement levels. Results from the NR method compare well with the standard resonant column method at the resonant frequency if the strain levels are the same. The NTF approach can be used to measure the dependence of phase velocity of shear waves with frequency. However, the NTF method cannot be used to measure the variation of material damping with frequency. On the other hand, the NR method can be used to measure the degradation curves of wave velocity and material damping ratio as a function of frequency. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A9%2813 [...]

Ultrasonic transducers characterisation for evaluation of stiff geomaterials / F. Tallavo in Géotechnique, Vol. 61 N° 6 (Juin 2011) 

Public ISBD [article]  in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 501–510 Titre : Ultrasonic transducers characterisation for evaluation of stiff geomaterials Type de document : texte imprimé Auteurs : F. Tallavo, Auteur ; G. Cascante, Auteur ; Pandey, M. D., Auteur Année de publication : 2011 Article en page(s) : pp. 501–510 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Laboratory  tests  Numerical  modelling  Dynamics  Waves  and  wave  loading Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The pulse velocity test (PVT) is an ASTM standard for the dynamic characterisation of geomaterials such as stiff clays, cemented sands, rooks and concrete. The PVT is based on the first arrival of the compressional wave. The analysis of full waveforms in ultrasonic testing is important in evaluating the variation with frequency of the dynamic properties of materials (phase velocity and material damping). Reliable full waveforms are also required to calibrate numerical simulations for the interpretation of ultrasonic wave propagation in viscoelastic materials. However, the analysis of full waveforms is rarely performed in practice because of the difficulties involved in the characterisation of ultrasonic transducers and their coupling with the medium. This paper presents a new methodology for measurement of the frequency response and impulse response functions of ultrasonic transducers. The proposed methodology uses the complex exponential method to extract dynamic properties from impulse response functions. Ultrasonic tests and numerical simulations are conducted on a calibration aluminium bar and a cemented sand specimen to demonstrate the applicability of the new methodology. The results show that this methodology can be successfully used for dynamic characterisation of ultrasonic transducers for evaluation of the wave velocity and damping ratio of stiff geomaterials. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.087 [article] Ultrasonic transducers characterisation for evaluation of stiff geomaterials [texte imprimé] / F. Tallavo, Auteur ; G. Cascante, Auteur ; Pandey, M. D., Auteur . - 2011 . - pp. 501–510. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 61 N° 6 (Juin 2011) . - pp. 501–510 Mots-clés : Laboratory  tests  Numerical  modelling  Dynamics  Waves  and  wave  loading Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : The pulse velocity test (PVT) is an ASTM standard for the dynamic characterisation of geomaterials such as stiff clays, cemented sands, rooks and concrete. The PVT is based on the first arrival of the compressional wave. The analysis of full waveforms in ultrasonic testing is important in evaluating the variation with frequency of the dynamic properties of materials (phase velocity and material damping). Reliable full waveforms are also required to calibrate numerical simulations for the interpretation of ultrasonic wave propagation in viscoelastic materials. However, the analysis of full waveforms is rarely performed in practice because of the difficulties involved in the characterisation of ultrasonic transducers and their coupling with the medium. This paper presents a new methodology for measurement of the frequency response and impulse response functions of ultrasonic transducers. The proposed methodology uses the complex exponential method to extract dynamic properties from impulse response functions. Ultrasonic tests and numerical simulations are conducted on a calibration aluminium bar and a cemented sand specimen to demonstrate the applicability of the new methodology. The results show that this methodology can be successfully used for dynamic characterisation of ultrasonic transducers for evaluation of the wave velocity and damping ratio of stiff geomaterials. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.087