An Evaluation of a Thermal Conductivity Sensor for the Measurement of Soil Matric Suction PDF Download
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Author: Daniel K. H. Wong
Publisher:
ISBN:
Category : Soil moisture
Languages : en
Pages :
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Book Description
Author: Daniel K. H. Wong
Publisher:
ISBN:
Category : Soil moisture
Languages : en
Pages :
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Author: A. Xing
Publisher:
ISBN:
Category : Matric suction sensor
Languages : en
Pages : 10
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Book Description
Thermal conductivity matric suction sensors appear to be a promising device for the measurement of suction in soil. The technique indirectly measures matric suction by measuring the thermal conductivity of a ceramic block. This paper uses both a spherical and a cylindrical porous medium to simulate the heat flow in a thermal conductivity matric suction sensor. It is found that, although the transient temperature at the center of the sensor is heavily dependent on the material of the thermocouple and the heating device, the steadystate temperature is primarily determined by the thermal conductivity of the ceramic block. Therefore, accurate measurements can be obtained by using a longer heating period or by selecting a lower-heat-capacity material for the thermocouple and the heating device. Optimal sizes of the sensor for given heating rates and heating periods are calculated using a finite difference method. A multilayered sphere was also used to simulate the situation where the size of the sensor is not sufficiently large and an error occurs due to the influence of the surrounding soil. The numerical model is verified by comparison with the theoretical solution of a special case.
Author: DG. Fredlund
Publisher:
ISBN:
Category : Calibration
Languages : en
Pages : 7
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Book Description
The accuracy of suction measurements using thermal conductivity sensors is dependent upon their calibration. Therefore, a calibration study was undertaken by using a modified, commercially available, pressure plate extractor. The experimental setup along with the calibration procedure are described. Typical calibration results are presented. In general, results showed reasonable agreement between the calibration curve determined in this study compared to those provided by the manufacturer for matric suction ranging from 0 to 175 kPa. However, large deviations in the calibration curves were observed at suctions above 175 kPa. The sensors were found to be quite sensitive to the changes in matric suction in the range of 0 to 175 kPa. For matric suction above 175 kPa, the sensitivity of the sensor is reduced.
Author: Alessandro Tarantino
Publisher: Springer Science & Business Media
ISBN: 1402088191
Category : Science
Languages : en
Pages : 214
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Book Description
This volume details recent global advances in laboratory and field testing of unsaturated soils. Coverage includes mechanical, hydraulic, and geo-environmental testing and applications of unsaturated soil monitoring to engineering behavior of geo-structures.
Author: Nan Zhang
Publisher:
ISBN:
Category : Soil matric potential
Languages : en
Pages : 263
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Book Description
Simultaneous measurement of soil thermal conductivity, moisture content, dry density, and soil suction is a challenging issue and very important to the design of geothermal-related structures such as geothermal energy piles (GEP), ground source heat pump (GSHP) systems, borehole thermal energy storage (BTES) systems, etc. The measurement of these properties is mainly done in laboratory conditions, which can be time consuming. Hence, an attempt is made in this research to develop a new field sensor that can provide these properties in about the same timeframe. The TDR technique has been used successfully to measure soil moisture content and dry density by analyzing the soil dielectric constant (Ka) and the electrical conductivity (ECb) obtained from TDR waveforms. The objective of this research is to develop a new thermo-time domain reflectometry (TDR) probe and a moisture/suction TDR probe to better achieve these measurements. The thermo-TDR probe has three probes of the same diameter and length, with resistance wire embedded in the center probe, and three thermocouples installed in each probe. The probe calibrations for Ka and ECb were completed by testing five different chemicals with known Ka values, and NaCl and KCl solutions with different concentrations. The probe was then evaluated by testing four different materials, i.e., three sands and kaolin clay, and validating them against the KD2 standard probe for measurement of soil thermal properties. Laboratory experiments employing the thermo-TDR probe were then performed on quartz sands, sand-sand mixtures, and sand-clay mixtures to study the effects of the quartz content, particle size, moisture content, dry density, and clay content on soil thermal conductivity. Based on the experimental results on sand-clay mixtures, a continuum soil thermal conductivity prediction model was developed. The model overcame the shortcomings of the existing models, which accounts for the quartz content effect and prediction of soil thermal conductivity continuously over the entire range of soil types. The moisture/suction TDR probe has two steel stainless probes and a gypsum block attached to half of the probes. The calibration of the probe is conducted by modified pressure plate tests to establish the relationship between Ka and the matric suction of the gypsum block. Laboratory experiments on silty sand, including the staged-drying test and absorption and desorption tests, were performed to evaluate the probe and to study the equilibrium or response time of the gypsum block being equilibrated with surrounding soils
Author:
Publisher:
ISBN:
Category : Arctic regions
Languages : en
Pages : 416
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Book Description
Author: Willy Alvarenga Lacerda
Publisher: Taylor & Francis US
ISBN: 9780415356664
Category : Science
Languages : en
Pages : 1810
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Book Description
Author: W. Lacerda
Publisher: CRC Press
ISBN: 0415356652
Category : Technology & Engineering
Languages : en
Pages : 1772
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Book Description
These volumes comprise the Proceedings of the Ninth International Symposium on Landslides, held in Rio de Janeiro, Brazil, from June 28 to July 2, 2004. Information on the latest developments in Landslide Studies is presented by invited lecture reports, specialized panel contributions and over two hundred and forty technical papers, grouped in the following themes: - Mapping and geological models in landslide hazard assessment, - Advances in rock and mine slopes design, - Field instrumentation and laboratory investigations, - Pre-failure mechanics of landslides in soil and rock, - Mechanisms of slow active landslides, - Post-failure mechanics of landslides, - Stabilization methods and risk reduction measures. A wealth of the latest information on all aspects of landslide hazard, encompassing geological modelling and soil and rock mechanics, landslide processes, causes and effects, and damage avoidance and limitation strategies.
Author: Adrian R. Russell
Publisher: CRC Press
ISBN: 1000115356
Category : Technology & Engineering
Languages : en
Pages : 907
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Book Description
This book contains the contributions to the Second European Conference on Unsaturated Soils, E-UNSAT 2012, held in Napoli, Italy, in June 2012, and includes more than one hundred papers, addressing three thematic areas: experimental, modelling, and engineering.
Author: Nasser Khalili
Publisher: CRC Press
ISBN: 1315749580
Category : Technology & Engineering
Languages : en
Pages : 1872
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Book Description
Unsaturated Soils: Research and Applications contains 247 papers presented at 6th International Conference on Unsaturated Soils (UNSAT2014, Sydney, Australia, 2-4 July 2014). The two volumes provide an overview of recent experimental and theoretical advances in a wide variety of topics related to unsaturated soil mechanics:- Unsaturated Soil Behavi
