英文篇名
INVESTIGATION ON SLOPE FAILURE INDUCED BY TYPHOON HERB AT LOW ELEVATION AREA AT ALI-SHAN HIGHWAY
作者
李德河、田坤國、黃嵩傑、林國忠
關鍵字
邊坡崩塌、預測、阿里山公路
摘要
賀伯颱風在阿里山公路沿線造成相當多之崩塌、滑動災害,本文則以低海拔路段之邊坡破壞為調查對象,嘗試瞭解其破壞的特性與誘發之因素。同時本文亦以阿里山公路26K+800m之邊坡上所設置之地表伸縮計、地下水位計以及氣象局設於瀨頭的雨量計等所量測得到之資料探討低海拔邊坡破壞時之實際變動情形,以及使用伸縮計及雨量計之觀測資料作為邊坡崩壞預測之適用性。
由調查結果顯示,阿里山公路低海拔路段之邊坡破壞多屬小規模之坡面淺層崩壞形式,其中自然邊坡產生崩壞者其坡度多在40度以上,而以40°~44°者居多,然而人工開發邊坡,其坡度在30°~34°左右便會產生破壞。
由26K+800m處所設置之伸縮計僅在淺層滑移發生前數分鐘才有較大之變化,顯示對於邊坡發生淺層崩壞的時間預測,只利用伸縮儀是不夠的,必須再掌握降雨量及地下水位變動的資料,方能有良好的預測成果。
英文摘要
Typhoon Herb attacked Taiwan and brought several disasters all around the island. The disasters occurred in hilly areas, especially the Ali-Shan highway, including slope failure, landslide and debris flow, etc. In order to understand the mechanism and find out the influential factors of the slope failure, the low elevation area on Ali-Shan highway was selected to promote this investigation work. This investigation was strengthened by the in-situ measurenont data acquired from extensometer and piezometer, which had installed in the slope at 26K+800m of Ali-Shan highway. These data are not only adopted to investigate the actual movement of slope, but also used to assess their suitability for predicting the time of slope failure.
The results of investigation showed that most slope failures occurred in low elevation areas of Ali-Shan highway being small scale and induced by the failure or erosion of heavily weathered layer. The slope angle of failed natural slope is greater than 40 degrees;however, quite a lot of man-developed slope were failed with a slope angle from 30°to 34°. A slope failure happened at 26K+800m, just few minutes after a significant movement of slope surface occurred. Although the movement was catched by an extensometer which had been installed there, it seems that only the extensometer without other instruments can not predict failure of a slope and alarm the danger perfectly. Therefore, the data regarding precipitation and variation of water table have to be included if the accuracy of slope failure prediction needs to be elevated.