基于布里渊光时域反射仪的边坡监测光纤传感器结构

Optical Fiber Sensing Structure for Slope Monitoring Based on Brillouin Optical Time Domain Reflectometer

分布式布里渊光纤传感技术在边坡监测领域中有极大的应用潜力。坡体局部产生的大应变往往会超过光纤的承受能力导致光纤断裂,并且由于系统空间分辨率的限制,难以获得一个准确的测量结果。为适应边坡监测,开发了用于分布式布里渊光纤传感的光纤传感结构,通过管子和滑轮构成具有保护作用的往返式结构,在短距离上增加了传感光纤的长度,不仅扩展了光缆对局部变形的耐受度,同时也提高了应变监测准确度。设计对比校准实验,验证了其在空间分辨率为1 m时的性能,并在人工浅层边坡上进行现场监测实验,验证了其对滑坡监测的有效性。此外,由于光缆在改良装置的保护下不与外界接触,光缆的存活率显著提高。

Distributed Brillouin optical fiber sensor has great potential for slope monitoring.The sensing fiber is easy to be broken due to extensive local strain,and it is often difficult to obtain accurate measuring results due to the limitation of the spatial resolution.In order to fit for the slope monitoring,an Optical Fiber Sensing Structure(OFSS)for the distributed Brillouin optical fiber sensing network is developed.The OFSS composes of a PVC pipe and two pulleys,constructing multiple round-trips for the sensing fiber.The length of sensing fiber for a short spatial length is extended significantly.So both the sensing accuracy and the tolerance to local deformation of the fiber are improved effectively.A comparative calibration experiment is designed in the laboratory to verify its performance with the spatial resolution of 1 m.What's more,the effect of the proposed OFSS for landslide monitoring is confirmed through an on-site monitoring test on a shallow artificial slope.In addition,since the optical cable has no contact with the outside under the protection of the modified device,the survival rate of the cable is increased significantly.