FBG弯曲传感在滑坡预警监测中的应用研究

Application of FBG bending sensors in landslide forecasting and monitoring

针对传统滑坡预警监测技术中存在的自动化程度较低、测量精度不高,不易对边坡实现大面积和长期可靠在线监测等不足,研究了采用光纤光栅(FBG)弯曲传感技术用于边坡表面形变及深部位移测量的结构原理及具体应用方式。在分析采用简支梁和悬臂梁两种结构实现FBG弯曲调谐原理的基础上,选择具有不同中心波长的FBG进行串接后,粘贴于弹性杆件PVC管上,实验验证了利用简支梁和悬臂梁两种FBG弯曲调谐结构实现边坡表面形变及深部位移进行原理性测量的可行性。实验结果表明,粘贴在PVC管上不同位置的FBG的波长变化量与该位置的形变量有着明显的线性对应关系;两种结构最大形变位置的FBG测量灵敏度分别为0.245nm/mm和0.166nm/mm;采用在PVC管两侧对称180°的位置粘贴FBG的方法,可在提高FBG检测灵敏度的同时,解决FBG温度及应变的交叉敏感问题,消除环境温度变化对FBG弯曲传感测量结果的影响。

In view of the problems such as less automation, low measurement accuracy, not easy use in the large area and lack of reliable online monitoring in the traditional landslide monitoring technologies, this paper uses fiber Bragg grating （FBO） bending sensing technology, and researches its structural principles and specific applications in measurement of slope surface deformation and deep displacement. On the ba- sis of analyzing the FBG bending sensing principle using simple supported beam and cantilever beam tun- ing structure, FBO series with different center wavelengths are selected and pasted on the PVC pipe. The principle feasibility using simple supported beam and cantilever beam tuning FBG bending sensing to test the slope surface deformation and deep displacement has been verified. Experimental results show that the FBG wavelength changes have a clear linear relationship with its pasting locations on PVC pipe. And the maximum Ft3G strain sensitivities are 0. 245 nm/mm and 0. 166 nm/mm respectively for the two beam tuning structures. In addition, using the method of pasting FBG on PVC pipe with symmetric 180° position, the FBG- detection sensitivity can be improved. Meanwhile, the influence of temperature changes on FBG bending sensor can be eliminated.