Fig. 1. Diagram of the experimental setup

Fig. 2. Principle diagram of the OFDR technology

Fig. 3. Temperature clouds of different profiles

Fig. 4. Temperature curves of thermometer and optical fiber

Fig. 5. Temperature clouds of different laying methods

Fig. 6. Temperature curve of different influence radius

Fig. 7. Temperature distribution in X-Z section under different conditions

Fig. 8. The fitting curve of temperature change ΔT and logarithm of time ln（t）under different conditions

Fig. 9. Variation curve of soil thermal conductivity with soil bulk density and water content

Fig. 10. Temperature distribution in Y-Z section under different water content

Fig. 11. Vertical distribution of soil temperature under different power