关键词: FBG光纤传感技术, 开口PHC管桩, 贯入阻力分离, 桩身应力, 临界深度

Abstract: The separation of side resistance and toe resistance of PHC pipe piles during installation restricts the study of its penetration mechanism and bearing capacity. Full-scale tests are conducted on 5 opened PHC pipe piles jacked into stratified soils to monitor the variation of side resistance and toe resistance during installation base on quasi-distributed Fiber Bragg grating sensors. The results indicate that quasi-distributed optical fiber technology has strong operability and installation resistance separation is obtained well under bad construction condition. The variation of pile jacking force in stratified soils basically reflects the soil parameters difference, and the soil under pile toe has more influence on jacking force. The test piles jacking force, which pile toe locates on bearing layer, increases about 64.06% when jacks into the bearing layer, while the increment of toe resistance and side resistance are 97.41% and 17.92%, respectively; The pile jacking force variation is not significant which toe doesn’t locate on bearing layer. The variation of pile stress in field test is different from indoor experiments during installation, in which the mechanism of side resistance in upper is different with bottom; and the critical depth phenomenon of side resistance is not obvious because of bad construction condition and soil variation in depth.

Key words: FBG optical fiber sensing technology, opened PHC pipe piles, penetration resistance separation, pile stress, critical depth