Performance evaluation of two types of heated cables for distributed temperature sensing-based measurement of soil moisture content

Dingfeng Cao 1, Bin Shi 1 *, Honghu Zhu 1 *, Kun Zhu 1, Guangqing Wei 2, Kai Gu 1

1 School of Earth Sciences and Engineering, Nanjing University, Nanjing, 210023, China

2 Suzhou NanZee Sensing Technology Co., Ltd., Suzhou, 215123, China

Journal of Rock Mechanics and Geotechnical Engineering, 2016, 8(2), 212-217.

DOI: 10.1016/j.jrmge.2015.09.005

Abstract: Distributed temperature sensing (DTS) using heated cables has been recently developed for distributed monitoring of in-situ soil moisture content. In this method, the thermal and electrical properties of heated cables have a significant influence on the measurement accuracy of soil moisture content. In this paper, the performances of two heated cables, i.e. the carbon-fiber heated cable (CFHC) and the metal-net heated cable (MNHC), are studied in the laboratory. Their structures, uniformity in the axial direction, measurement accuracy and suitability are evaluated. The test results indicate that the MNHC has a better uniformity in the axial direction than CFHC. Both CFHC and MNHC have high measurement accuracy. The CFHC is more suitable for short-distance measurement (≤500 m), while the MNHC can be used for long-distance measurement (>500 m).

Key words: soil moisture content; carbon-fiber heated cable (CFHC); metal-net heated cable (MNHC); distributed measurement; optical fiber


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