Study on a calibration equation for soil water content in field tests using time domain reflectometry
Yun Zhao, Dao-sheng Ling, Yun-long Wang, Bo Huang, Han-lin Wang
MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Zhejiang University, Hangzhou 310027, China; Institute of Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China
Abstract The crucial point in calibrating soil water content using the technology of time domain reflectometry (TDR) is to establish the relationship between the apparent dielectric constant and the water content. Based on a database, which included 45 kinds of soil samples and 418 data points from our own test data and relevant literature, an empirical calibration equation is proposed. Additionally, the influence of soil type, dry density of soil, compaction energy, pore fluid conductivity, and temperature on the calculated result for water content was also analyzed. Results show that the equation can offer an error of ±0.05 g/g for most soils encountered in geotechnical engineering. However, the estimation error given by the empirical equation becomes significant for soils with dry density less than 1.3 g/cm3, so the equation was modified to consider the influence of dry density. Both of the empirical equations can be used to test gravimetric water content using the TDR method conveniently and efficiently without calibration.
Yun Zhao, Dao-sheng Ling, Yun-long Wang, Bo Huang, Han-lin Wang. Study on a calibration equation for soil water content in field tests using time domain reflectometry. Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2016, 17(3): 240-252.
Al Emran Ismail, Ahmad Kamal Ariffin, Shahrum Abdullah, Mariyam Jameelah Ghazali, Mohammed Abdulrazzaq, Ruslizam Daud. Stress intensity factors under combined bending and torsion moments[J]. Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2012, 13(1): 1-8.
