A distributed measurement method for in-situ soil moisture content by using carbon-fiber heated cable

Dingfeng Cao a, Bin Shi a,*, Honghu Zhu a,*, Guangqing Wei b, Shen-En Chen c, Junfan Yan a

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

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

c Department of Civil and Environmental Engineering, University of North Carolina at Charlotte, NC 28223, USA

Journal of Rock Mechanics and Geotechnical Engineering, 2015, 7(6), 700-707.

DOI: 10.1016/j.jrmge.2015.08.003

Abstract

Moisture content is a fundamental physical index that quantifies soil property and is closely associated with the hydrological, ecological and engineering behaviors of soil. To measure in-situ soil moisture contents, a distributed measurement system for in-situ soil moisture content (SM-DTS) is introduced. The system is based on carbon-fiber heated cable (CFHC) technology that has been developed to enhance the measuring accuracy of in-situ soil moisture content. Using CFHC technique, a temperature characteristic value (Tt) can be defined from temperaturee-time curves. A relationship among Tt, soil thermal impedance coefficient and soil moisture content is then established in laboratory. The feasibility of the SM-DTS technology to provide distributed measurements of in-situ soil moisture content is verified through field tests. The research reported herein indicates that the proposed SM-DTS is capable of measuring in-situ soil moisture content over long distances and large areas.

Keywords: In-situ soil moisture content, Distributed measurement, Carbon-fiber heated cable (CFHC), Fiber-optic sensing


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