加勁擋土結構物光纖安全監測研發與應用

Abstract

台灣地區現有數百座加勁擋土結構物，但至今還未有一可長久且穩定的量測與安全監測方法。光纖光柵（Fiber Bragg Grating, FBG）柔軟細小，有不怕雷擊、不受電磁波干擾沒有受潮短路問題以及同一條光纖上可以安裝多個FBG等優點，但光纖在拉伸應變1%時即斷裂，而加勁拉應變經常大於10%。本研究使用光纖光柵做為感測元件，將光纖光柵與加勁材以15度之夾角結合以分量的方式降低其應變量，成為加勁材應變計，並將光纖光柵加勁材應變計於室內做拉伸與模型試驗，並進行現場測試安裝。本論文敘述將FBG黏貼於加勁材之技術以及敘述現有之試驗結果。

Hundreds of reinforced earth structures have been built in Taiwan. Yet, there is still a lack of long-term, reliable means to monitor the safety for these structures. Optical fiber Bragg Grating, FBG has the advantages of being minute, immune to lightning, electromagnetic interference and short circuit, and capable of connecting multiple FBG’s using a single optical fiber. However, the optical fiber breaks when it is subject to 1% in tensile strain which is significantly lower than that experienced in the geosynthetic fibers under working conditions. This research intends to use FBG as the main strain sensing unit. The FBG is aligned at 15% from lateral direction and fixed to the geosynthetic fibers so that only a fraction of the strain is applied to the FBG’s. The FBG’s serve as strain gages. The method was experimented in a series of laboratory extension and physical model tests as well as a field installation. The thesis describes the techniques of attaching FBG to the geosynthetic material and results from laboratory and field experiments.