A generalized thermal conductivity model for soils and construction materials

Côté, Jean; Konrad, Jean‐Marie

doi:10.1139/t04-106

Cited by 616 publications

(400 citation statements)

References 13 publications

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“…The obtained results concerning the untreated sand are validated using the empirical model of Coté & Konrad (2005). The value of the degree of saturation corresponding to each measurement of the thermal conductivity is determined at the end of the test, once the steady state is reached (approximately after 3 h).…”

Section: Alrtimimentioning

confidence: 99%

“…Table 4 summarises the standard deviation between the obtained values for the untreated material and those predicted by several semi-empirical models expressing λ as a function of S. Each of these models uses different fitting parameters. Results were compared with the models of Johansen (1975), Hu et al (2001), Coté & Konrad (2005), Lu et al (2007) and the square-root model. In particular, a good agreement is found with the models developed by Coté & Konrad (2005) and Lu et al (2007) .…”

Section: Alrtimimentioning

confidence: 99%

“…Results were compared with the models of Johansen (1975), Hu et al (2001), Coté & Konrad (2005), Lu et al (2007) and the square-root model. In particular, a good agreement is found with the models developed by Coté & Konrad (2005) and Lu et al (2007) . Having the lowest standard deviation, this latter model for coarse sand has been found to be the best to fit the measures proposed by authors…”

Section: Alrtimimentioning

confidence: 99%

“…It assumes different expressions depending on the considered model: for Coté & Konrad (2005) the expression becomes…”

Section: Q8mentioning

confidence: 99%

“…The obtained values for the MICP-treated sample are compared with the λ value of the untreated sand calculated according to the formula by Coté & Konrad (2005) [equation (4)]. …”

Section: Q8mentioning

confidence: 99%

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Microbially induced calcite precipitation effect on soil thermal conductivity

Venuleo

Laloui

Terzis

et al. 2016

Géotechnique Letters

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Efficiency of energy piles is strongly affected by soil saturation conditions: low water contents considerably decrease their performance thus limiting the possibility to extend their application to arid environments. This paper investigates the microbially induced calcite precipitation (MICP) technique as a potential means of enhancing the soil–pile heat exchange rates by improving the thermal properties of soil. The study puts the focus on measuring the thermal conductivity of untreated and treaded sand at various degrees of saturation. Experimental results clearly show a significant improvement of the thermal conductivity of soil especially for low degrees of saturation. This enhancement is attributed to the mineralised calcite crystals acting as ‘thermal bridges’ between the soil grains, offering a larger surface area for heat exchange compared with the untreated material in which exchanges occur through smaller contact points.

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Section: Alrtimimentioning

confidence: 99%

Section: Alrtimimentioning

confidence: 99%

Section: Alrtimimentioning

confidence: 99%

“…It assumes different expressions depending on the considered model: for Coté & Konrad (2005) the expression becomes…”

Section: Q8mentioning

confidence: 99%

“…The obtained values for the MICP-treated sample are compared with the λ value of the untreated sand calculated according to the formula by Coté & Konrad (2005) [equation (4)]. …”

Section: Q8mentioning

confidence: 99%

See 3 more Smart Citations

Microbially induced calcite precipitation effect on soil thermal conductivity

Venuleo

Laloui

Terzis

et al. 2016

Géotechnique Letters

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Estimation of land surface water and energy balance parameters using conditional sampling of surface states

et al. 2014

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Numerical models of heat and moisture diffusion in the soil-vegetation-atmosphere continuum are linked through the moisture flux from the surface to the atmosphere. This mass flux represents a heat exchange as latent heat flux, coupling water, and energy balance equations. In this paper, a new approach for estimating key parameters governing moisture and heat diffusion equation and the closure function which links these equations, is introduced. Parameters of the system are estimated by developing objective functions that link atmospheric forcing, surface states, and unknown parameters. This approach is based on conditional averaging of heat and moisture diffusion equations on land surface temperature and moisture states, respectively. A single objective function is expressed that measures moisture and temperaturedependent errors solely in terms of observed forcings and surface states. This objective function is minimized with respect to the parameters to identify evaporation and drainage models and estimate water and energy balance flux components. The approach is calibration free (surface flux observations are not required), it is not hampered by missing data and does not require continuous records. Uncertainty of parameter estimates is obtained from the inverse of Hessian of the objective function, which is an approximation of the error covariance matrix. Uncertainty analysis and analysis of the covariance approximation, guides the formulation of a well-posed estimation problem. Accuracy of this method is examined through its application over three different field sites. This approach can be applied to diverse climates and land surface conditions with different spatial scales, using remotely sensed measurements.

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Modeling and analysis of evaporation processes from porous media on the REV scale

Mosthaf

Helmig

2014

Water Resour. Res.

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The dynamics of drying processes from porous media are critically influenced by the intensity of an adjacent free flow and by processes at the interface between free flow and the porous medium. In this paper, the influence of hydraulic properties of a porous medium and of the interaction between fluids and porous medium on the drying dynamics during the capillary-flow dominated stage-1 and transition to the diffusion-dominated stage-2 are studied using a coupled free-flow-porous-medium flow model on the REV scale. We present a detailed model concept that considers mass balance equations, an energy balance equation, and the coupling to the adjacent free flow. Key microscale processes are identified and incorporated in the macroscale description of the evaporation process. Own experimental results are used to illustrate main features of the modeling framework. We demonstrate that the use of a homogeneous distribution of soil parameters without consideration of pore-scale induced nonlinearities in the numerical simulations results in a rather constant drying rate in stage-1, which was not observed for the high evaporative demand in the experiments. To account for the dependency of the drying rate on the surface moisture content, special conditions based on the work of Haghighi et al. (2013) and Schl€ under (1988) are analyzed for their applicability on the REV scale. Typical features of a drying process, such as different stages of the drying rate, could be reproduced.

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A generalized thermal conductivity model for soils and construction materials

Cited by 616 publications

References 13 publications

Microbially induced calcite precipitation effect on soil thermal conductivity

Microbially induced calcite precipitation effect on soil thermal conductivity

Estimation of land surface water and energy balance parameters using conditional sampling of surface states

Modeling and analysis of evaporation processes from porous media on the REV scale

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