Thermal Conductivity of Sand–Silt Mixtures

Roshankhah, Shahrzad; Garcia, Adrian; Santamarina, J. Carlos

doi:10.1061/(asce)gt.1943-5606.0002425

Cited by 24 publications

(5 citation statements)

References 64 publications

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“…The field data were obtained from Prince Albert weather station, with a silty soil closely matching the investigated material [103]. Such soils have a hydraulic conductivity range of 10 −5 to 10 −7 m/s [86,94] and a thermal conductivity range of 0.0007 to 0.0029 kJ/s/m• • C [121,122]. The hydraulic (Figure 5b) and thermal (Figure 5c) properties of the investigated soil fell within the above range and, as such, the model was considered to adequately capture field conditions.…”

Section: Resultsmentioning

confidence: 99%

A Transient Seepage–Thermal Stability Model for Cohesionless Soil Slopes in the Semi-Arid Continental Climate of the Canadian Prairies

Akram,

Azam

2023

Sustainability

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Seasonal weather variations have a profound effect on the integrity of cohesionless soil slopes in the Canadian Prairies owing to the prevalent semi-arid continental climate. The primary contribution of this research is the development of a transient and two-dimensional stability model that is fully coupled with hydraulic and thermal flows. The model was used to predict the factor of safety (FS) for two slope geometries (18 m height and 26 m height) subjected to three weather scenarios (mean, extreme wet, and extreme dry) and four ponding combinations on the upstream and downstream sides of the slopes under no-load and train-load conditions. Results indicated that for mean climate conditions, FS trends fluctuate till April, followed by an increase that remains constant up to November and decreases thereafter. Generally, the FS shows subdued fluctuations and higher values for the high slope compared with the low slope. For wet climate conditions, the FS patterns are similar to mean conditions, albeit with reduced durations of stability during summer. For dry climate conditions, FS values are higher than mean conditions and nearly constant for most of the year. For no ponding and downstream ponding, FS > 1 throughout the year. In contrast, FS > 1 only during the summer (with reduced time in wet climate and extended time in dry climate conditions) for upstream ponding and upstream–downstream ponding. For train loading, FS shows subdued fluctuations and lower values than the corresponding no-loading scenarios for both slopes. The effects of climate conditions and ponding scenarios are further reduced for the high slope. These findings are useful for decision making with regard to the initial design and ongoing performance of natural slopes and embankments in the cohesionless soils of the region.

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Section: Resultsmentioning

confidence: 99%

A Transient Seepage–Thermal Stability Model for Cohesionless Soil Slopes in the Semi-Arid Continental Climate of the Canadian Prairies

Akram,

Azam

2023

Sustainability

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“…This outcome follows, for instance, a study by Busby et al [41], where dry sand had the least thermal conductivity and silt had the highest thermal conductivity values. Pure sand showing very low heat extraction values is comprehensible because of its low water holding capacity; thus, the thermal connectivity can be notably diminished [42]. Busby et al showed that only values for saturated soil exceed the thermal conductivity of silt.…”

Section: Discussionmentioning

confidence: 99%

Development of a Calculation Concept for Mapping Specific Heat Extraction for Very Shallow Geothermal Systems

2022

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Horizontal shallow geothermal applications are easy to install, and their installation process is less liable to legislation than other geothermal systems. Due to a lack of planning guidance, the opportunity to implement such systems is often overlooked, although geothermal installations are urgently needed as a sustainable energy source. To give a foundation for including very shallow geothermal systems in local heat supply planning, potential maps are crucial. To enable their utilization in energy use plans or similar elaborations for municipalities, location-specific and system-specific heat extractions are required. Since applicable standards are not available, it is nearly impossible to provide aggregate propositions, which are essential for potential maps. In this study, a concept was evolved for deriving very shallow geothermal potential maps with location-specific and system-specific heat extraction values. As a basis, VDI 4640 Part 2 information regarding heat extraction and respective climate zone references was utilized. Furthermore, climate information and a soil map were needed to apply the concept to the study area. The application of the concept in an Austrian study area resulted in appropriate potential maps. Moreover, this concept is similarly applicable in other areas of interest.

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“…The analysis of the effective range (spatial dependence), was defined as the distance at which the semivariance value achieves 95% of the sill, and indicated that it was lower for the thermal properties of the in situ than for the laboratory measurements. The lower spatial dependence of the thermal properties in situ could be influenced for the most part by the effect of the spatially differentiated soil water content and bulk density and the associated air-filled porosity and also by the more stable organic matter content (Abu-Hamdeh and Reeder, 2000;Schjønning, 2021) as well as the textural and mineralogical composition (Usowicz et al, 2020;Roshankhah et al, 2021;Schjønning, 2021). This explanation may be supported by the greater effective ranges in the cross-semivariograms including soil thermal properties as primary variables and sand content as a secondary variable.…”

Section: Discussionmentioning

confidence: 99%

Spatial variability of thermal properties in relation to the application of selected soil-improving cropping systems (SICS) on sandy soil

Usowicz¹,

Lipiec²

2022

Int. Agrophys.

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The study aimed to determine the effect of randomly applied soil-improving cropping systems on the variability of soil thermal conductivity, heat capacity, and thermal diffusivity over the course of a 3-year (2016-2018) study. The field experiment included the control and the following soil-improving cropping systems: liming, leguminous catch crops for green manure, farmyard manure, and liming+leguminous catch crops+farmyard manure together with spring oats (2017) and spring wheat (2018). The parameters such as bulk density, water content, and values of soil thermal conductivity, heat capacity, and thermal diffusivity have been determined. The thermal properties were measured at the current water content in situ and in water-saturated and dry soil states in the laboratory. The thermal properties in the wet year of 2017 increased in the subareas with a predominance of leguminous catch crops for green manure, farmyard manure, and liming+leguminous catch crops+farmyard manure, whereas the soil-improving cropping systems effect was not consistent after stubble tilling in the dry year of 2018. Cross-semivariograms which used the sand content as an auxiliary variable and cokriging produced a better prediction than the semivariograms and kriging. The fractal analysis indicated that the number of subareas differing in thermal properties was mainly modified by water content and bulk density. The spatial spread of the soil thermal properties during the water-saturated and dry states increased in subareas with a higher bulk density.K e y w o r d s: soil-improving practices, thermal conductivity, heat capacity, thermal diffusivity, semi-and cross-semivariograms, kriging and cokriging, mapping

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Thermal Conductivity of Sand–Silt Mixtures

Cited by 24 publications

References 64 publications

A Transient Seepage–Thermal Stability Model for Cohesionless Soil Slopes in the Semi-Arid Continental Climate of the Canadian Prairies

A Transient Seepage–Thermal Stability Model for Cohesionless Soil Slopes in the Semi-Arid Continental Climate of the Canadian Prairies

Development of a Calculation Concept for Mapping Specific Heat Extraction for Very Shallow Geothermal Systems

Spatial variability of thermal properties in relation to the application of selected soil-improving cropping systems (SICS) on sandy soil

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