Resonant Column Tests on Partially Saturated Sands

Knodel, PC; Qian, Xiaolei; Gray, D. H.; Woods, R. D.

doi:10.1520/gtj10571j

Cited by 58 publications

(10 citation statements)

References 6 publications

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“…These studies denoted a higher shear modulus and lower damping in partially saturated soils due to the presence of inter-particle suction stresses that increase the soil stiffness. Results by Qian et al (1991) and Ghayoomi and McCartney (2011) indicated a general increase in small-strain shear modulus of sands up to a peak value before the residual water content. However, a continuous rise of modulus was reported by Khosravi and McCartney (2011) as suction increases in silty material.…”

Section: Introductionmentioning

confidence: 95%

“…In recent years, theoretical and experimental advancements in understanding the behavior of unsaturated soils have revealed the importance of the degree of saturation on the shear modulus and damping in geomaterial. Small-strain moduli (0.0001 %-0.01 %) of various soils under different degrees of saturation using the resonant column and bender element tests have been extensively investigated and several empirical relations were proposed (Wu et al 1984;Qian et al 1991;Marinho et al 1995;Mancuso et al 2002;Mendoza et al 2005;Ng et al 2009;Khosravi et al 2010;Khosravi and McCartney 2011;Ghayoomi and McCartney 2011;Kumar and Madhusudhan 2012;Hoyos et al 2015). These studies denoted a higher shear modulus and lower damping in partially saturated soils due to the presence of inter-particle suction stresses that increase the soil stiffness.…”

Section: Introductionmentioning

confidence: 99%

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Cyclic Direct Simple Shear Test to Measure Strain-Dependent Dynamic Properties of Unsaturated Sand

Ghayoomi

2017

Geotech. Test. J.

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The dynamic properties of a clean sand under different degrees of saturation were investigated using a modified custom built Direct Simple Shear (DSS) apparatus at the University of New Hampshire. The specific characteristics of the DSS were presented, and the testing procedures were discussed. The device used the axis translation and tensiometric techniques to control the matric suction in the soil specimen. The investigation on F75 Ottawa Sand showed a decrease in shear modulus and an increase in damping by increasing the shear strain over the tested range of strains for various degrees of saturation: dry, saturated, and partially saturated. The modulus reduction in the applied range of medium shear strains regardless of the degree of saturation demonstrated the capability of the DSS in consistently capturing the changes of dynamic properties. Experimental results indicated that the matric suction can have a substantial effect on the stiffness of the soil. However, the extent of this effect may depend on the induced strain level of the effective stress in unsaturated soil. In addition, partially saturated specimens resulted in lower dynamic compression.

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Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Cyclic Direct Simple Shear Test to Measure Strain-Dependent Dynamic Properties of Unsaturated Sand

Ghayoomi

2017

Geotech. Test. J.

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“…Experimental difficulties, such as direct measurement and control of matric suction, have hindered the investigation of the dynamic behavior of unsaturated soils. Although researchers have increasingly explored the effect of degree of saturation on the dynamic soil modulus and damping, they have mostly focused on the small-strain shear modulus for various suction values or degrees of saturation using bender element or resonant column tests (Wu et al 1984;Qian et al 1991;Marinho et al 1995;Cho and Santamarina 2001;Mancuso et al 2002;Mendoza et al 2005;Alramahi et al 2008;Ng et al 2009;Khosravi et al 2010;Hoyos et al 2015). In addition, in some recent studies, researchers investigated the effect of suction on the strain-dependent shear modulus, soil volume change, stress path, pore pressure, and drainage conditions in cyclic triaxial systems (Cui et al 2007;Craciun and Lo 2010;Biglari et al 2011;Kimoto et al 2011;Cary and Zapata 2016).…”

Section: Introductionmentioning

confidence: 99%

Cyclic Triaxial Test to Measure Strain-Dependent Shear Modulus of Unsaturated Sand

2017

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Dynamic shear modulus plays an important role in the seismic assessment of geotechnical systems. Changes in the degree of water saturation influence dynamic soil properties because of the presence of matric suction. This paper describes the modification of a suctioncontrolled cyclic triaxial apparatus to investigate the strain-dependent shear modulus of unsaturated soils. Several strain-and stress-controlled cyclic triaxial tests were performed on a clean sand with various degrees of saturation. Suction in unsaturated sands increased the shear modulus in comparison with the ones in dry and saturated conditions for different shear strain levels, with a peak modulus in higher suction levels. Also, shear modulus decreased with an increase in the shear strain for specimens with similar matric suction. The normalized shear moduli of the unsaturated sand specimens followed a similar trend to the ones predicted by the available empirical shear modulus reduction functions but showed lower values. The modulus reduction ratios of unsaturated sands shifted up as a result of higher effective stress and suction-induced stiffness. These trends were consistent for both strain-and stress-controlled tests.

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“…Temporal variations in the seismic velocities of partially saturated earthworks are therefore likely related to changes in capillary/suction pressures, which in turn may result from seasonally or climatically related variations in soil moisture. Several authors have explored the relationship among S-wave velocity, degree of saturation, and soil suction on laboratory samples for a range of materials (Qian et al, 1991;Marinho et al, 1995;Cho and Santamarina, 2001;Mancuso et al, 2002;Donohue and Long, 2010). The experimental results suggest that measurements of V S are sensitive to changes in saturation and soil suction.…”

Section: Introductionmentioning

confidence: 99%

Time-lapse monitoring of climate effects on earthworks using surface waves

et al. 2016

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The UK's transportation network is supported by critical geotechnical assets (cuttings/embankments/dams) that require sustainable, cost-effective management, while maintaining an appropriate service level to meet social, economic, and environmental needs. Recent effects of extreme weather on these geotechnical assets have highlighted their vulnerability to climate variations. We have assessed the potential of surface wave data to portray the climate-related variations in mechanical properties of a clay-filled railway embankment. Seismic data were acquired bimonthly from July 2013 to November 2014 along the crest of a heritage railway embankment in southwest England. For each acquisition, the collected data were first processed to obtain a set of Rayleigh-wave dispersion and attenuation curves, referenced to the same spatial locations. These data were then analyzed to identify a coherent trend in their spatial and temporal variability. The relevance of the observed temporal variations was also verified with respect to the experimental data uncertainties. Finally, the surface wave dispersion data sets were inverted to reconstruct a time-lapse model of S-wave velocity for the embankment structure, using a least-squares laterally constrained inversion scheme. A key point of the inversion process was constituted by the estimation of a suitable initial model and the selection of adequate levels of spatial regularization. The initial model and the strength of spatial smoothing were then kept constant throughout the processing of all available data sets to ensure homogeneity of the procedure and comparability among the obtained V S sections. A continuous and coherent temporal pattern of surface wave data, and consequently of the reconstructed V S models, was identified. This pattern is related to the seasonal distribution of precipitation and soil water content measured on site.

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Resonant Column Tests on Partially Saturated Sands

Cited by 58 publications

References 6 publications

Cyclic Direct Simple Shear Test to Measure Strain-Dependent Dynamic Properties of Unsaturated Sand

Cyclic Direct Simple Shear Test to Measure Strain-Dependent Dynamic Properties of Unsaturated Sand

Cyclic Triaxial Test to Measure Strain-Dependent Shear Modulus of Unsaturated Sand

Time-lapse monitoring of climate effects on earthworks using surface waves

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