将分布式光纤监测技术应用于土体变形监测时,传感光缆与周围土体的耦合性是关键。低围压下光缆-土体变形协调性将严重影响测量数据的准确性。设计了锚固光缆,进行了光缆-土体拉拔试验,探究了低围压下回填料及锚固方式对光缆-土体耦合性的影响。试验结果表明:回填料对光缆-土体耦合性存在明显的影响,黏土含量(质量分数)越高,耦合性越好;低围压下,采用在传感光缆上增加圆片锚固的方式,可以有效增强光缆-土体耦合性,并且随着锚固间距的减小和锚固圆片直径的增大,其耦合性增强。

The coupling of the sensing cable to the surrounding soil is essential to the application of distributed optical fiber monitoring technology for monitoring soil deformation, particularly the coordination of fiber-soil deformation under low confining pressures, which seriously affects the accuracy of the measurement data. In this study, the anchored fiber-optic cable is designed and the fiber-soil pull-out test is performed to investigate the effects of backfill material and anchoring method on fiber-soil coupling under low confining pressures. Results show that the backfill material considerably affects the fiber-soil coupling. The higher the clay content is, the better the coupling is. Under low confining pressures, the fiber-soil coupling can be effectively enhanced by adding the wafer anchor into the sensing cable. Decreasing anchor interval and increasing anchor diameter can improve the fiber-soil coupling.