Development of a Large-Scale Infiltration Column for Studying the Hydraulic Conductivity of Unsaturated Fouled Ballast

Duong, Trong Vinh; Trinh, Viet-Nam; Cui, Yu‐Jun; Tang, Anh Minh; Calon, Nicolas

doi:10.1520/gtj20120099

Cited by 30 publications

(20 citation statements)

References 34 publications

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“…(Duong et al, 2013) a Bell (1992) b Banks et al (2013) c Banks (2012) d Selig & Waters (1994) From Smethurst et al, 2015). Note that the symbols mark the maximum extent of installation and that the tree location, form and height are not to scale.…”

Section: Discussionmentioning

confidence: 99%

“…The clay fill was assigned a lower air entry value and a curve of shallower gradient than the in situ London Clay, reflecting its greater specific volume and wider range of pore sizes, following Loveridge et al (2010) and Briggs et al (2013a). A SWRC for fouled ballast (given by Duong et al, 2013) was used to model the ash / ballast layer at the site.…”

Section: Materials Propertiesmentioning

confidence: 99%

“…The London Clay foundation soil was assigned ksat = 5 × 10 -9 ms -1 , consistent with in situ London Clay (Chandler et al, 1990;O'Brien et al, 2004). The ash and ballast layer was assigned ksat = 1.75 × 10 -5 ms -1 (Duong et al, 2013).…”

Section: Materials Propertiesmentioning

confidence: 99%

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The influence of tree root water uptake on the long term hydrology of a clay fill railway embankment

Briggs

Smethurst

Powrie

et al. 2016

Transportation Geotechnics

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This paper uses a numerical model to investigate the influence of tree root water uptake and tree removal on pore water pressures and the vertical movement of a clay fill railway embankment. Simulated results of soil wetting and drying are compared with field measurements from an instrumented railway embankment before and after tree removal. A parametric study compares the influence of vegetation on the seasonal movement of the embankment slope. The simulations and field measurements show that while trees cause significant seasonal variations in pore water pressure and water content near the soil surface, they can maintain persistent soil suctions at depth within the tree rooting zone. Demonstration of this result using a numerical model requires a root water uptake function that separates spatially the processes of water infiltration, evaporation and transpiration. With all of the trees are removed, the persistent soil suctions established by the trees are lost as water infiltrates from the soil surface. Leaving the trees in place over the bottom third of the slope can maintain persistent suctions at the slope toe, while potentially also reducing seasonal ground movements at the crest that may adversely affect railway track geometry.

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Section: Discussionmentioning

confidence: 99%

Section: Materials Propertiesmentioning

confidence: 99%

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The influence of tree root water uptake on the long term hydrology of a clay fill railway embankment

Briggs

Smethurst

Powrie

et al. 2016

Transportation Geotechnics

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“…( [7]) All sensors were checked and calibrated in laboratory before installation work. Calibration of TDR probes included the effects of temperature, soil type and soil unit mass upon the measured values ( [16,18,19,20,21,22,23]). The influence of temperature upon the measurement with strain gauges was also checked in laboratory and included into calibration.…”

Section: Figure 2 Grain Size Distributionmentioning

confidence: 99%

Experiences from in-situ monitoring of pavement under weather conditions change

et al. 2016

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Abstract. Very strong winters with temperatures under 0°C and hot summers with temperatures more than 30°C are observed in the South East part of Slovenia. Those big differences in temperature during the year and especially temperatures below freezing point have strong influence on asphalt layer and sub base of road pavement. The freeze/thaw cycles lead to formation of ice lenses in base course causing cracks in asphalt layers and degrade the pavement usually in a few years. For this reason one section of the national road in the South East part of Slovenia was rebuilt with cold in-situ pavement retreatment. A test field with inbuilt sensors for measuring water content, temperature and deformation in various depths and locations was constructed during the remediation works to study the mechanism of freeze-thaw degradation of pavements. The main goal of the test field is to determine water content in sub base, freezing depth, temperature distribution and deformations, which lead to cracks in asphalt layer after the remediation work in the road construction.

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“…However, many studies have shown that hydraulic conductivities computed in the laboratory tend to have a smaller mean and a larger variance than conductivities observed in the field over larger scales (Chapuis et al, 2005;Clauser, 1992;Parker & Albrecht, 1987;Rovey & Niemann, 1998;Sobieraj, Elsenbeer, & Cameron, 2004;Yang et al, 2017). In any case, scale effects may vary according to measurements conditions, geological characteristics and the spatial correlation length of hydraulic conductivity in a specific site (Neuman, 1994; (Duong, Trinh, Cui, Tang, & Calon, 2013;Khan & Jury, 1990;Lai & Ren, 2007), resulting in a lack of knowledge that we hope to contribute to reduce.…”

Section: Introductionmentioning

confidence: 99%

Upscaling of water flow and mass transport in a tropical soil: numerical, laboratory and field studies

Godoy¹

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Numerical models are becoming fundamental tools to predict a range of complex problems faced by geotechnical and geo-environmental engineers. However, to render the model reliable for future predictions, the model input parameters must be determined with consideration of the scale effects. If there is a difference of scales between the observation and the model scales there are two possible ways to consider it: or models are constructed with elements of a size similar to that at which the data were measured, or some upscaling rules must be defined. In this context, this thesis focuses on upscaling of water flow and mass transport in a tropical soil by means of numerical, laboratory and field studies. This thesis is organized in four parts.First, the heterogeneity, correlation and cross-correlation between solute transport parameters (dispersivity, α, and partition coefficient, Kd) and soil properties are studied in detail. In this part, it is verified that the hydraulic conductivity (K) and solute transport parameters are highly heterogeneous, while soil properties are not. Spatial correlation of α, K, and statistically significant variables are studied, and it would probably improve the estimation only in a small-scale study, since the spatial correlation are only observed up to 2.5 m. This study is a first attempt to evaluate the spatial variation in the correlation coefficient of transport parameters of a reactive and a nonreactive solute, indicating the more relevant variables and the one that should be included in future studies.In the second part, scale effect on K, dispersivity and partition coefficient of potassium and chloride are studied experimentally by means of laboratory and field experiments. The purpose is to contribute to the discussion about scale effects on K, α and Kd and understanding how these parameters behave with the change in the scale of measurement. Results show that K values increases with scale, regardless of the method of measurement, except for the results obtained from double-ring x infiltrometer tests. Dispersivity trends to increase exponentially with the sample height.Partition coefficient tends to increase with sample length, diameter and volume. These differences in the parameters according to the scale of measurement must be considered when these observations are later used as input to numerical models, otherwise the responses can be misrepresented.Third, stochastic analysis of three-dimensional hydraulic conductivity upscaling is performed using a simple average and the Laplacian-with-skin methods for a variety of block sizes based on real K measurements. In this part it is demonstrated the errors that can be introduced by using a deterministic upscaling using simple averages of the measured K without accounting for the spatial correlation. Results show that K heterogeneity can be incorporated in the daily practice of the geotechnical modeler.The aspects to consider when performing the upscaling are also discussed. Finally, the dependence of the exponent of the p-norm as a...

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Development of a Large-Scale Infiltration Column for Studying the Hydraulic Conductivity of Unsaturated Fouled Ballast

Cited by 30 publications

References 34 publications

The influence of tree root water uptake on the long term hydrology of a clay fill railway embankment

The influence of tree root water uptake on the long term hydrology of a clay fill railway embankment

Experiences from in-situ monitoring of pavement under weather conditions change

Upscaling of water flow and mass transport in a tropical soil: numerical, laboratory and field studies

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