Fig. 1. Working principle diagram of static level

Fig. 2. Schematic diagram of principle of single fiber Bragg grating static level before settlement

Fig. 3. Schematic diagram of principle of single fiber Bragg grating static level after settlement

Fig. 4. Equal strength cantilever beams and fiber Bragg grating

Fig. 5. Schematic diagram of double fiber Bragg grating static level before settlement

Fig. 6. Schematic diagram of double fiber Bragg grating static level after settlement

Fig. 7. Structural design drawing of double fiber Bragg grating static level

Fig. 8. Exploded assembly drawing of leak-proof connecting device

Fig. 9. Vernier caliper as height ruler, and physical drawing of equal strength cantilever beams. (a) Vernier caliper as height ruler; (b) physical drawing of equal strength cantilever beams

Fig. 10. Calibration test of double fiber Bragg grating static level

Fig. 11. Relationship between sum of positive travel wavelength variation values of three groups and settlement variation, and fitting curve

Fig. 12. Relationship between sum of reverse travel wavelength variation values of three groups and settlement variation, and fitting curve

Fig. 13. Engineering application of double fiber Bragg grating static level

Fig. 14. Monitoring curve of uneven settlement between two columns