Study on calibration model of soil water content based on actively heated fiber-optic FBG method in the in-situ test

In the water content measurement technology based on actively heated fiber-optic (AHFO) method, how to establish the calibration model between the temperature characteristic value and the water content is very important. Given shortcomings of the existing calibration models, the optimal calibration model was established. On this basis, a modified calibration model considering the change of dry density was proposed by using the actively heated fiber-optic fiber Bragg grating (AHFO-FBG) method, and the feasibility of the model was verified and analyzed. The results show that the Cote and Konrad model is the best model for water content calculation; in the in-situ water content measurement, if the dry density of the soil is small (<= 1.5 g/cm(3)), the modified Cote and Konrad calibration model should be used. The research results are of great significance to guide the application of the AHFO-FBG method in the insitu soil water content monitoring. (C) 2020 Elsevier Ltd. All rights reserved.