Tensile Strength of Unsaturated Sand

Lu, Ning; Kim, Tae-Hyung; Sture, Stein; Likos, William J.

doi:10.1061/(asce)em.1943-7889.0000054

Cited by 145 publications

(92 citation statements)

References 14 publications

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“…During imbibition, similar to the experimental G max data, a hysteresis behavior in p s was observed, with values of suction stress being lower than those during drainage. The predicted SSCC is consistent with those reported by [14].…”

Section: Characterization Of the G Max Behavior For Sandy Specimenssupporting

confidence: 82%

“…In this study, an attempt was made to define relationships between G max and effective stress using the concept of suction stress introduced by [13]. The suction stress is a stress variable that incorporates the effect of different inter-particle stresses arising from chemical cementation, van der Waals attraction, capillarity, and double layer repulsion into the effective stress definition for unsaturated soils [13][14][15]. The suction stress can be easily defined from shear/tensile strength tests data or using a closed-form mechanical expression proposed by [16] as follows:…”

Section: Characterization Of the G Max Behavior For Sandy Specimensmentioning

confidence: 99%

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Characterizing the variation of small strain shear modulus for silt and sand during hydraulic hysteresis

et al. 2016

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Abstract. Experimental studies have indicated that the small strain shear modulus, Gmax, of unsaturated silt and clay has a greater amount during imbibition than during drainage, when presented as a function of matric suction. However, due to material properties and inter-particle forces, different behavior is expected in the case of sand. Although considerable research has been devoted in recent years to characterize the behaviour of Gmax of sand during drainage, rather less attention has been paid to the effect of hydraulic hysteresis on Gmax and its variations during imbibition. In the study presented herein, an effort has been made to compare the Gmax behavior of specimens of silt and sand during hydraulic hysteresis. In this regard, a series of bender element tests were carried out in a modified triaxial test device with suction-saturation control to evaluate the impact of hydraulic hysteresis on Gmax for specimens of silt and sand. Trends between the Gmax and matric suction for unsaturated sand were found to be different from those for silty specimens. The variations in Gmax showed an up and down trend in both drainage and imbibition paths for sandy specimens, where plotted as a function of matric suction. Results also indicated smaller magnitudes of Gmax upon imbibition than those during drainage; a behavior which is believed to be attributed to variations in suction stress with matric suction. In silty specimens, a stiffer response was measured during imbibition which was hypothesized to be due to drainage-induced hardening experienced by the specimens that was not fully recovered during imbibition.

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Section: Characterization Of the G Max Behavior For Sandy Specimenssupporting

confidence: 82%

Section: Characterization Of the G Max Behavior For Sandy Specimensmentioning

confidence: 99%

Characterizing the variation of small strain shear modulus for silt and sand during hydraulic hysteresis

et al. 2016

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“…The tensile strength of the unheated sand corresponds with the data of Patterson and Boenisch (1961) which also observed a strong increase of tensile strength with an increasing water content from 2 to 3 wt.% and a strong decrease when the water content increases further. The increase in tensile strength is in accordance with the theoretical model of Lu et al (2009) for sands. The decrease at higher water contents indeed indicates a clay-like behaviour (Lu et al 2010).…”

Section: Tensile Strengthsupporting

confidence: 75%

“…3 wt.%. The observed initial increase of green tensile strength with water content is in accordance with the numerical model derived by Lu et al (2009) for the tensile strength of moist sands. For clay, the numerical model of Lu et al (2010) yields a negative correlation of tensile strength with increasing moisture.…”

Section: Tensile Strengthsupporting

confidence: 71%

Neutron Radiographic Study of the Effect of Heat-Driven Water Transport on the Tensile Strength of Bentonite-Bonded Moulding Sand

et al. 2017

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Wet tensile testing is a common method to assess the stability of bentonite-bonded moulding sands. For wet tensile testing, a specimen is first heated from above in order to simulate heat-driven moisture transport induced by the casting process. Then, tensile stress is applied until rupture. In this study, neutron radiography imaging was applied to moulding sands in situ during heating and wet tensile testing in order to investigate the effects of water kinematics on the tensile strength. Neutron radiography allowed the localization of the rupture plane and the quantitative determination of the local water content with sub-mm resolution. Quantification of the temperature at the rupture plane and of the heat kinematics within the specimen was accomplished by temperature measurements both in situ and ex situ. In this way, experimental data correlating the wet tensile strength with the specific conditions of moulding sands at the rupture plane were obtained for the first time. that the weakest location within a sand profile can be pinpointed at the interface between evaporation and condensation zone (i.e. at the 100 • C isotherm), where water vaporization starts and the water bridges connecting the sand grains collapse. This weakest location has maximum strength, if the local water content at the rupture plane is between 5 and 9 wt.%. Less water leads to a strong decrease of wet tensile strength. More water requires an initial water content above 5 wt.%, which leads to a decrease of the tensile strength of the unheated sand.

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“…The tensile strength may be determined by substituting apparent cohesion, the third term from equation (14), into the definition for tensile force given by Lu et al [2009], yielding…”

Section: Force Balance On the Sliding Blockmentioning

confidence: 99%

Infiltration and instability in dune erosion

Palmsten

Holman

2011

J. Geophys. Res.

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[1] Forecasting dune erosion prior to a storm or over longer periods requires knowledge of the fluid forces on the dune sediments. To improve our predictive capability for this process, we propose a new model in which dune slumping occurs when water, which infiltrates horizontally into the dune, increases the overburden sufficiently to destabilize the dune. Horizontal infiltration is driven by suction of water from swash into the dune via capillary action and is a surprisingly strong process with rapid time scales. Because the elevated pore water concentrations increase the apparent cohesion of the wetted sediments, we also propose that the entire volume of wetted sand slumps as a unit when the dune becomes unstable and erosion can be modeled based on the force balance on a sliding block. Several versions of this model were tested, including a numerical infiltration model, a simplified infiltration equation, and an equation based on offshore wave forcing, rather than known forcing at the dune. The model was tested using data from a large-scale laboratory experiment with a storm hydrograph to investigate the time dependence of dune erosion. Predicting slope stability using a numerical infiltration model with known forcing explained 72% of the observed variance in erosion rate, while a simplified stability and infiltration model explained 58%. Error statistics suggest that we captured the majority of the physics controlling dune erosion in this laboratory experiment and that the simplified model will be useful as a forecasting tool.

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Tensile Strength of Unsaturated Sand

Cited by 145 publications

References 14 publications

Characterizing the variation of small strain shear modulus for silt and sand during hydraulic hysteresis

Characterizing the variation of small strain shear modulus for silt and sand during hydraulic hysteresis

Neutron Radiographic Study of the Effect of Heat-Driven Water Transport on the Tensile Strength of Bentonite-Bonded Moulding Sand

Infiltration and instability in dune erosion

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