削坡作用土质边坡变形分布式光纤监测试验研究

ANALYSIS ON THE STRAIN-FIELD OF SOIL CUT SLOPE BASED ON DFOS TECHNOLOGY MONITORING

采用高空间分辨率的PPP-BOTDA光纤感测技术,研发出一种适合于土体变形监测的特种感测光缆。通过水平向和垂直向感测光缆植入,对边坡模型在坡顶局部加载和削坡过程土体内部变形场进行了分布式监测,获得了荷载和削坡作用下坡体变形场的分布规律,并对边坡模型进行了有限元数值分析和计算评价。分布式光纤感测技术监测结果表明:在坡顶局部加载作用下土体水平向拉张变形最大值发生在坡体中部,这与数值模拟结果一致;但在削坡作用下,坡体水平向拉张变形最大值发生在坡体上部,表明削坡作用改变了边坡模型的变形规律,上层土体在坡顶局部荷载作用下易发生倾倒变形。研究结果也表明,作者研制的特种感测光缆具有良好的感测性能,可以对土体变形场进行准确有效监测。

A slope model was conducted in the laboratory and a special strain sensing cable was buried in the soil mass. The sensing cable strain at different position of the slope model was measured by the pulse-prepump Brillouin optical time-domain analysis（ PPP-BOTDA） technology during the loading and cut the slope. Then the test processing was simulated by the finite element analysis software Geo- studio. The measurement data under the loading have been analyzed to discuss the co-deformation between the sensing cable and the soil mass. The results show that the co- deformation was affected by the confining pressure significantly. The measurement data of the sensing cable during cut slope showed that there was strain concentration area in the soil mass. When the slope failed,the position of the sliding surface was consistent with the strain anomaly area of the sensing cable. The results provide a guiding to evaluate slope stability and perform early warning of landslides.