Fig. 1. Sensing principle of FBG

Fig. 2. (a) Structure and (b) installation of FBG strain sensors with low temperature sensitivity

Fig. 3. Relationship between central wavelength variation and temperature under three temperature tests

Fig. 4. Relationship between the sensor central wavelength and bare FBG. (a)、(b)、(c) are sensors 1,2, 3, respectively

Fig. 5. FBG sensors distribution diagram

Fig. 6. Variations of pile shaft force.(a), (b), (c), (d) are pile shafts SZ1, SZ2, SZ3, SZ4, respectively

Fig. 7. Variations of toe resistance and sides resistance during installation. (a), (b), (c), (d) are pile shafts SZ1, SZ2, SZ3, SZ4, respectively