Determination of Shear-Wave Velocities and Shear Moduli of Completely Decomposed Tuff

Ng, Charles Wang Wai; Leung, Erin H. Y.

doi:10.1061/(asce)1090-0241(2007)133:6(630)

Cited by 23 publications

(7 citation statements)

References 15 publications

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“…The loss of shear wave velocity from in situ to the laboratory ranged between 14% (block samples) to nearly 50% for some of the tube samples. Ng and Wang [50], Ng et al [52], and Ng and Leung [51] also measured shear wave velocities on block specimens of completely decomposed granite and tuff, reporting values around 30% higher than those of the Mazier specimens. More recently, Rocchi and Coop [60] reported small disturbance on Mazier-collected specimens on Hong Kong residual soil, which may be a result of the grading characteristics of the soil and to a higher weathering degree.…”

Section: Assessment Of Sampling Quality By Comparison Of Seismic Wavementioning

confidence: 98%

Getting high-quality samples in ‘sensitive’ soils for advanced laboratory tests

Fonseca

Pineda

2017

Innov. Infrastruct. Solut.

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Laboratory tests are well recognized as highly appropriate for defining the engineering properties of geomaterials, in terms of constitutive law parameters for modeling geotechnical engineering problems. The strong development of advanced techniques, both in equipment and in data interpretation, has increased the confidence in laboratory testing, while on the other hand the limitations due to the quality of soil sampling with depth and the spatial representativeness of the samples are less consensual. Still, the development of new methods for assuring high-quality samples is increasing, together with sampling quality assessment by non-destructive methods using vibration wave velocities. Interpretation methods of in situ tests for ground characterization have also evolved significantly, increasing the reliability of these methods. Their versatility to cover large areas on site and the fact that these tests are, in principle, performed at the actual state (physical and stress) conditions, as well as the improvements in the correlations between field tests and hydraulic and geomechanical parameters, allow joining the quality of data and theoretical approaches, namely through critical state soil mechanics. This keynote paper discusses some of the aspects that can and should enable the association of ground characterization from laboratory testing over undisturbed samples used in more or less advanced tests, enhancing the determinant conditioning factor, that is, the sampling technique to get representative specimens and the way this is assessed. The confidence that we expect to have on the geomechanical parameters that we need for our geotechnical activities will mostly depend on this in view of the high uncertainties of the parametrical correlations with in situ test data, therefore, important in ground characterization. This is especially relevant in sensitive soils, such as soft fine soils, loose sandy soils, or young residuals soils. These have or can have ''weak'' equilibria of the interparticle micro-and macrostructures (or their arrangement, fabric) that will change substantially their properties if samples are collected and conditioned with processes that do not preserve that intrinsic ''ADN''. The change in these natural conditions can be evaluated by techniques of quality assessment, which will be discussed in what follows.

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Section: Assessment Of Sampling Quality By Comparison Of Seismic Wavementioning

confidence: 98%

Getting high-quality samples in ‘sensitive’ soils for advanced laboratory tests

Fonseca

Pineda

2017

Innov. Infrastruct. Solut.

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“…Extensive investigations have revealed that G 0 can be affected by confining pressure, void ratio (e), overconsolidation ratio, soil gradation, particle properties, and so on [6][7][8][9][10][11]. Among these factors, confining pressure and void ratio have been widely investigated [12][13][14][15][16][17][18], and their effects can be well-characterized by Hardin's equation, as follows:…”

Section: Introductionmentioning

confidence: 99%

Characterizing the Effect of Water Content on Small-Strain Shear Modulus of Qiantang Silt

Zhang

Liu

et al. 2021

JMSE

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Due to the impact of natural and artificial influence, such as waves, tides, and artificial dewatering, the small-strain shear modulus of soils may vary with the water content of soil, causing deformation of excavations and other earth structures. The present study used a resonant column device to investigate the effects of water content, void ratio, and confining pressure on the small-strain shear modulus of a silt extracted from an excavation site near Qiantang River in Hangzhou, China. The test results revealed that the effects of the three factors are not coupled and can be characterized by three individual equations. In particular, the small-strain shear modulus decreases with increasing water content under otherwise similar conditions, which can be characterized by a power function. The classical Hardin’s equation is modified to consider the effect of water content by introducing an additional function of water content.

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“…Photoelastic analysis and discrete element modeling of glass beads found that the preferential force-chains and local arching through spherical particles were developed (Nadukuru and Michalowski 2012;Santamarina et al 2001). For nonspherical particles, including clay minerals, fabric anisotropy plays a major role (Kang et al 2014;Ng and Leung 2007;Pennington et al 1997;Santamarina et al 2001). Due to the geological sedimentation process and high overburden stress (Bellotti et al 1996), platy clay particles are often aligned in a preferentially horizontal structure under K 0 consolidation (Kang et al 2014;Santamarina et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Shear Wave Velocity and Its Anisotropy of Polymer Modified High-Volume Class-F Fly Ash–Kaolinite Mixtures

Kang

Bate

2016

J. Geotech. Geoenviron. Eng.

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This study investigated the effects of polymers on the small-strain stiffness behavior of high volume Class-F fly ash-kaolinite mixtures. The shear wave velocity (V s ) and its anisotropy of organically modified fly ash-kaolinite mixtures were evaluated using a selfdeveloped floating wall type consolidometer bender element (BE) testing system. Both synthetic polymers [polyethylene oxide (PEO)] and biopolymers (xanthan gum and chitosan) were used to modify the stiffness of fly ash-kaolinite mixtures. Shear waves generated and received by bender elements were measured to quantify the small-strain stiffness of the organically modified fly ash-kaolinite mixtures in three orthogonal directions, i.e., vh, hv, and hh. The results suggested that (1) as the fly ash content increased, V s increased, while the V s anisotropy, in terms of shear wave velocity ratio V s−hh =V s−vh , decreased; (2) a threshold fly ash content concept, which corresponds to the onset of continuous contact chains between fly ash particles throughout the specimen, was used to distinguish the kaolinite-dominated zone from the fly ash-dominated zone of V s and V s anisotropy behavior; (3) the introduction of fly ash was also found to enhance the crossanisotropy of fly ash-kaolinite mixtures; (4) the addition of PEO and chitosan increased the V s of the fly ash-kaolinite mixtures, while the addition of xanthan gum decreased the V s ; and (5) all three polymers were found to decrease the V s anisotropy of the fly ash-kaolinite mixtures.

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Determination of Shear-Wave Velocities and Shear Moduli of Completely Decomposed Tuff

Cited by 23 publications

References 15 publications

Getting high-quality samples in ‘sensitive’ soils for advanced laboratory tests

Getting high-quality samples in ‘sensitive’ soils for advanced laboratory tests

Characterizing the Effect of Water Content on Small-Strain Shear Modulus of Qiantang Silt

Shear Wave Velocity and Its Anisotropy of Polymer Modified High-Volume Class-F Fly Ash–Kaolinite Mixtures

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