The Measurement of Unfrozen Water Content in Freezing Soils by Time Domain Reflectometry PDF Download
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Author: Daniel Edward Patterson
Publisher:
ISBN:
Category : Soil freezing
Languages : en
Pages : 138
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Book Description
Author: Daniel Edward Patterson
Publisher:
ISBN:
Category : Soil freezing
Languages : en
Pages : 138
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Book Description
Author: D. E. Patterson
Publisher:
ISBN:
Category :
Languages : en
Pages : 14
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Book Description
A portable, nondestructive method for measuring the unfrozen water content of frozen soils using time domain reflectometry (TDR) to measure the dielectric property.
Author: David J. Mulla
Publisher:
ISBN:
Category : Runoff
Languages : en
Pages : 178
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Book Description
Author: Cold Regions Research and Engineering Laboratory (U.S.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 17
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Book Description
The results of a laboratory testing program, carried out to compare two independent methods for determining the unfrozen water content of soils, are described. With the time domain reflectometry method, the unfrozen water content is inferred from a calibration curve of apparent dielectric constant vs volumetric water content, determined by experiment. Previously, precise calibration of the TDR technique was hindered by the lack of a reference comparison method, which nuclear magnetic resonance now offers. This has provided a much greater scope for calibration, including a wide range of soil types and temperature (unfrozen water content). The results of the testing program yielded a relationship between dielectric constant and volumetric unfrozen water content that is largely unaffected by soil type, although a subtle but apparent dependency on the texture of the soil was noted. It is suggested that this effect originates from the lower valued dielectric constant for absorbed soil water. In spite of this, the general equation presented may be considered adequate for most practical purposes. The standard error of estimate is 0.015 cc/cc, although this may be reduced by calibrating for individual soils. Brief guidelines on system and probe design are offered to help ensure that use of the TDR method will give results consistent with the relationship presented. Keywords: Dielectric constant; Frozen soils; Soils tests; Time domain reflectometry. (edc).
Author: M. W. Smith
Publisher:
ISBN:
Category :
Languages : en
Pages : 2
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Book Description
Describes method for measuring the unfrozen water content in frozen in situ soil samples.
Author: Michael W. Smith
Publisher:
ISBN:
Category :
Languages : en
Pages : 37
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Book Description
Examines the use of electromagnetic methods for measuring the unfrozen water content of freezing soils.
Author: Michael W. Smith
Publisher:
ISBN:
Category : Frozen ground
Languages : en
Pages : 24
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Book Description
Author: Michael W. Smith
Publisher:
ISBN:
Category : Soil freezing
Languages : en
Pages : 74
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Book Description
Author:
Publisher:
ISBN:
Category : Frozen ground
Languages : en
Pages : 348
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Book Description
Author: Zhen Liu
Publisher:
ISBN:
Category : Frozen ground
Languages : en
Pages : 9
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Book Description
The soil water characteristic curve (SWCC) is the basis to explain a variety of processes in unsaturated soils, ranging from transport phenomena to mechanical behaviors. In this paper, a new method is developed for SWCC estimation based on the similarity between the freezing/thawing process and drying/wetting process in soils. The theoretical basis for this method is first reviewed. The concept of the soil freezing characteristic curve (SFCC) is introduced to describe the relationship between the unfrozen water content and matric suction in frozen soils. SFCC is analogous to SWCC in that both of them describe the energy status of liquid water associated with liquid water content. Relationships between SWCC and SFCC are discussed. To measure the SFCC, a thermo-time domain reflectometry (TDR) sensor was developed which combines both temperature sensors and conventional TDR sensor. The TDR module and algorithm measured the bulk free water content of soils during the freezing/thawing processes, while the built-in thermocouples measured the internal temperature distribution. SFCCs were obtained from the simultaneously measured TDR and temperature data. Experiments were conducted on a few types of soils to validate this new procedure. The SFCC was obtained from thermo-TDR data collected in specimens subjected to a controlled thawing process, while the SWCC was directly measured by ASTM D5298, the filter paper method. Reasonable agreements were found between SWCC and SFCC. The experimental results implied that the SWCC could be estimated from SFCC, which also provided more evidence of the similarity of freezing/thawing processes and desorption/sorption processes.
