Abstract
Thermal conductivity of soil is a basic physical property related to heat conduction, and also is one of parameters widely applied in geotechnical engineering. The effect of gradation on the thermal conductivity of fused quartz was analyzed by thermal needle tests. The different particle size with the same uniformity coefficient (Cu = 3.2) and different uniformity coefficient for the same particle size (0.10~1.00 mm) were considered in this study. It shows that the thermal conductivity of fused quartz decreases with the decreasing of the mean particle size and with the increasing of the porosity. Simple modified methods to estimate the value of thermal conductivity are proposed, and had been demonstrated successfully by conducting fused quartz, carbonate sand and Ottawa sand.
Highlights
Thermal conductivity of soil is a basic physical property related to heat conduction, and is one of parameters widely applied in geotechnical engineering
Xiao et al.[15] found that the gradation effect on the thermal conductivity is attributed to the same intrinsic mechanism, which is independent of the porosity
Previous literature shows that the relationships between thermal conductivity (λ) and uniformity coefficients (Cu = d60/d10) for different porosity are parallel, indicating that the gradation effect on the thermal conductivity is attributed to the same intrinsic mechanism, which is independent of the porosity[15]
Summary
Thermal conductivity of soil is a basic physical property related to heat conduction, and is one of parameters widely applied in geotechnical engineering. Combined with laser and particle image velocimetry, non-invasive measurements can be made to investigate internal flow, deformation of transparent soil around the structure, grouting, and thermal reponse of sands in geotechnical engineering[6]. Previous literature has not studied the thermal properties of fused quartz and its difference in thermal behavior from that of natural soils. Measured thermal conductivity of fused quartz will be beneficial to future studies on thermal reponses of granular materials using transparent sand. This study reviews literature models for the thermal conductivity of granular materials, experimentally determines the thermal conductivity of fused quartz using the thermal needle probe method, and assesses the accuracy of predicting the measured data using the existed models. The results hightlight the inadequacy of these models in characterizing the measured thermal conductivity of fused quartz and a new fitting formula based on literature models is suggested
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