Feasibility study on FBG-based monitoring method for ice content in frozen soil

The ice content is an important parameter in frozen soil research. Aiming at the limitation of the existing ice content measurement, a method based on fiber Bragg grating (FBG) for monitoring the ice content in frozen soil is proposed. Based on the temperature field of frozen soil, a series of indoor calibration tests are performed using the FBG corundum tube sensor with internal heating. The corresponding function model between characteristic value of temperature and ice content is deduced and verified using the experimental data. The results show that the proposed method is feasible to monitor the ice content in frozen soil, the characteristic value of temperature decreases with the increase of ice content in frozen soil, and the approximate range of ice content can be preliminarily judged by this law. In the fitting of the function model, the exponential function model has the highest fitting degree with the experimental data, and the measurement error of ice content is less than 2% within the acceptable range.