藉由微機電系統觀測蘭台地區邊坡之滑動情形

Abstract

臺灣地區有三分之二以上的面積為山坡地，且時常受到颱風豪雨及地震的侵襲，導致大型坡地發生崩塌並造成災害。而在蘭台地區太平山森林遊樂園之聯外道路宜專一線曾受到坡地崩塌之影響而損壞。根據前人文獻，該區域之道路及擋土結構，皆經過多次修補，且於現地調查時可觀察到道路有多處裂縫及崩崖陷落等崩塌潛勢特徵。 微機電系統(MEMS)是一種結合半導體製程技術與精密機械技術來製造微小元件及功能整合的系統，是一個新興的領域，具有強大的功能、低廉的價格、縮小的體積以及智慧化等優點，對外力作用以及環境變化感應非常敏銳，適合作為觀測山地邊坡潛勢崩塌及微地動的工具，研究中所使用之MEMS以加速度計為主。 本研究主要透過長期監測觀測蘭台地區於平時、降雨事件及地震事件發生時的加速度紀錄，觀察蘭台地區的邊坡的滑動情形，透過快速傅立葉轉換將降雨事件及地震事件的加速度紀錄轉換至頻譜作觀察，瞭解在事件中地盤反應出的振動頻率，也透過傾斜角度的轉換以及愛氏強度(Arias intensity)轉換並繪製成玫瑰圖的方式，觀測蘭台地區長期邊坡傾斜角度的變化情形以及邊坡滑動的方向。 研究結果顯示，在地震事件中，MEMS反應出的當地卓越頻率約為5~7Hz，在降雨事件及地震事件中，頻譜均觀測到有特定頻率17Hz出現的情形，長期觀測的傾斜角度也有持續增加，並在發生增加的時間同樣觀測到特定頻率17Hz的出現，推估這個頻率可能是蘭台地區發生地滑時，地盤反應的振動頻率。玫瑰圖的結果也顯示出所觀測之邊坡為容易滑動之邊坡，且滑動方向大約與坡邊坡向一致的情形。

More than two-thirds of the area in Taiwan is hillside, and which is oftenly affected by typhoon, rains, and earthquakes. Those phenomenon cause the collapse of large slopes and disasters. In the joint road of Lantai Taipingshan National Forest Recreation Area should be a special line, which has been affected by the collapse of the slope damage. According to the former researches, the road and the retaining structure of the area have been repaired many times, the collapse potential of the road has many cracks, and collapse cliffs. Microelectromechanical systems (MEMS) has a strong function, low price, reduced size and wisdom, etc. It is very sensitive to the external force and the change of the environment, and it is suitable as the tool for observing the shallow collapse and ambient noise. The results show that in the event of earthquakes, the dominat frequency is about 5 ~ 7 Hz. In the event of rainfall events and earthquakes, the frequency is observed at 17 Hz with specific frequency, and the inclination angle of long-term observation is also increasing. The occurrence of an additional frequency of 17 Hz was observed at the time of increasing, and the frequency of the site reaction was estimated when the frequency was likely to slip. The result of the Wind Rose also shows that the slope is sliding and the sliding direction is approximately the same as the slope direction.