降雨引致地下水位變動對公路邊坡穩定影響之研究

Investigating on the Influence of Groundwater Variation Induced by Rainfall on the Stability of Highway Slope

曾國鈞(Kuo-Chun Tseng) ； 李德河(Der-Her Lee) ； 林宏明(Hung-Ming Lin) ； 吳建宏(Jian-Hong Wu)

《中華防災學刊》 8卷2期 (2016/08) Pp. 201-211

摘要

近年來全球暖化現象引發嚴重氣候變遷，極端氣候頻發也使得臺灣的降雨型態產生改變，對山多平原少的臺灣山區邊坡形成有異於往常的威脅。為了瞭解近年來降雨行為改變對我國南部山區邊坡防災工作之衝擊，本研究以進入阿里山國家森林遊樂區的主要道路（臺18線）和連結臺灣東西向山區交通的南部橫貫公路（臺20線）之代表性邊坡做為研究對象，探討降雨對不同地質條件的公路邊坡穩定性的影響，兩路段都是臺灣南部山區重要的路線，其暢通性和安全性是道路使用人和公路單位所嚴重關心的。本研究選擇臺18線公路之崩積層邊坡和臺20線公路之砂頁岩互層邊坡做為研究對象。除了收集相關的雨量、地質資料外，並進行地層鑽探及地電阻探測，用以瞭解邊坡的地層分佈。同時也設置傾斜觀測管、地下水位計以觀測邊坡變動及地下水的變化等。經由觀測取得試驗邊坡的地層構造、地下水位變動和邊坡變動方向及地層變動深度等資料，進而探討降雨量與地下水位變動量，以及降雨量與地層變動間的關係，最後透過極限平衡法對邊坡作穩定分析。

關鍵字

邊坡穩定 ； 降雨量 ； 地下水位變動

並列摘要

The rainfall patterns in Taiwan changed in recent years due to the impact of global warming and climate change. In this study, groundwater variation at colluvium slope located in Taiwan Highway No. 18 and alternating sandstone and shale slope located at Taiwan Highway No. 20 were investigated. Besides collecting the local precipitation and geology information, borehole drilling and electrical resistivity tomography test were performed to clarify the depth and the distribution of the underground geologic formations. In addition, monitoring devices, such as inclinometers and ground water level meters, were installed to monitor the slope and ground water level. Finally, the finite element analysis was conducted to integrate the results from observed geology soil layer structure, permeability of bedrock, slope sliding direction, and depth of sliding to the result of limit equilibrium method.

並列關鍵字

Slope stability ； Rainfall ； Groundwater variation