標題: Investigation of non-unique relationship between soil electrical conductivity and water content due to drying-wetting rate using TDR
作者: Chung, Chih-Chung
Lin, Chih-Ping
Yang, Shi-Hui
Lin, Jhe-Yi
Lin, Chun-Hung
土木工程學系
Department of Civil Engineering
關鍵字: Time domain reflectometry (TDR);Soil water content;Electrical conductivity (EC);Hysteresis;Drying-wetting rate
公開日期: 26-Mar-2019
摘要: The characterization of the relationship between volumetric soil water content (theta) and bulk electrical conductivity (EC) (or electrical resistivity) is of high interest in fields of engineering, fundamental petrophysical, hydrological model parameterization, and quantitative hydrogeophysical interpretations. Based on the relationship, for instance, the broad-area image using electrical resistivity tomography (ERT) can be transformed into theta tomograms as initial/boundary conditions of the slope stability analysis. However, the relationship is affected by the hysteresis, leading the inconsistency in drying-wetting circles. Therefore, this study focused on the factor of soil drying-wetting rate using the proposed time domain reflectometry (TDR) method and related sensors for such characterization. A modified pressure plate apparatus enhanced by TDR was first employed with a relatively low rate in which EC and theta were measured simultaneously, without evident non-unique relationship. A TDR penetrometer was then designed for acquiring the temporal variations of theta and EC in the field. On the basis of certain assumptions, observations showed an apparent dependency of the slope of the theta-EC rating curve on rates, but no hysteresis pattern. Finally, a laboratory controlled fast wetting drying cell was used to increase the response time, proving that both the hysteresis and slopes of the theta-EC rating curves were obviously affected by the soil drying-wetting rate, as a significant finding to the related topics.
URI: http://dx.doi.org/10.1016/j.enggeo.2019.02.025
http://hdl.handle.net/11536/152337
ISSN: 0013-7952
DOI: 10.1016/j.enggeo.2019.02.025
期刊: ENGINEERING GEOLOGY
Volume: 252
起始頁: 54
結束頁: 64
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