土石流光纖監測系統可行性研究

Feasibility Study of Debris Flow Fiber Optic Monitoring Systems

台灣位於歐亞板塊和菲律賓板塊之交界，由於板塊之互相擠壓作用，常常有地震發生。近年來受九二一地震及多次颱風豪雨引發之土石流影響，加上人為隨意開發，沒有植被來保護地表，使地表直接受大雨沖刷。因此，各地常有土石流發生，造成房舍損毀、人員傷亡，更常有重大災難事件頻傳。許多監測方法及技術先後被提出，但多屬傳統機電式方法，而土石流發生區域都於深山峻谷，電力供應不易，光纖由於具備低損耗及寬頻特性，近年來已取代同軸電纜成為通訊系統的主流，而干涉儀因具備高靈敏度，故常被應用在長距離、微弱訊號的偵測方面。因此，我們選擇光纖感測系統，來做為土石流監測系統，在我們多次實驗室內人工水槽試驗之結果，顯示，本光纖感測系統可偵測出土石流的主要頻率，分布在20～200Hz 的範圍內，其結果與用地聲感測器（geophone）偵測系統在相同之頻率範圍內之結果相近，因此證明光纖感測系統，可以運用在土石流監測。

Taiwan lies at the boundary of the Eurasia plate and Philippine's plate. Because of the interactions of these plates, earthquakes take place quite often. Due to the influence of the 921 earthquake and numerous typhoons and many torrential rains in recent years, the geography is changed. In addition, after the randomly development and abuse of the natural resources, the land surface itself is exposed to the torrential rain without any protection. So, debris flow happens. Sometimes, there is a great disaster accident that causes the damage of the house, the injury of people. Many detecting schemes and technologies were proposed, but most of them were belonged to traditional electrical types. In general, the area with potentially debris flow dangerous is usually located in the far away mountain area where the electric power supply is very difficult. Also, the long distance transmission makes the signal attenuate very fast. Because the optical fiber has the features of low transmission loss and wide bandwidth, it has replaced the coaxial cable as the mainstream of the communication system in recent years. Because of the high sensitivity characteristic, the fiber optic sensors are usually applied for long distance weak signal detection. Hence, we choose fiber optic sensors as the debris flow monitoring system and analyze its feasibility.