台灣山區淺層崩塌地特性調查與分析

Investigation and Analysis of the Characteristics of Shallow Landslides in Mountainous Areas of Taiwan

詹勳全(Hsun-Chuan Chan) ； 張嘉琪(Chia-Chi Chang) ； 陳樹群(Su-Chin Chen) ； 魏郁軒(Yun-Shiuan Wei) ； 王昭堡(Zhao-Bao Wang) ； 李桃生(Tao-Sheng Lee)

《中華水土保持學報》 46卷1期 (2015/03) Pp. 19-28

https://doi.org/10.29417/JCSWC.201503_46(1).0003

摘要

台灣為擁有特殊地理環境的島嶼，地質上受板塊互相擠壓作用影響，造山運動頻仍，這也使得台灣地形陡峻、地質破碎，加上氣候上降雨量豐沛，各地山區之坡地無法避免地受坡地崩塌的威脅，坡地一旦發生崩塌常威脅附近保護對象之安全，連帶造成人員傷亡。本研究以1999年921地震後之181處淺層崩塌區位為案例，透過現場調查與資料蒐集方式，瞭解台灣山區淺層崩塌地的特性，提供坡地災害防治策略擬訂之參考，藉以減少坡地崩塌可能造成之生命財產損失。研究結果顯示，台灣山區淺層崩塌多發生於東南至西向坡、坡度小於50度、高程小於1200公尺、且地質為三峽群及其相當地層及廬山層者；主要觸發崩塌之原因為降雨；此外，本研究藉由調查分析崩塌地之面積及體積，得到崩塌面積與崩塌體積呈對數線性相關，可供後續評估崩塌量體之參考。

關鍵字

淺層崩塌 ； 崩塌特性 ； 崩塌體積

並列摘要

Taiwan is an island with special geographical environments. The oblique convergence of tectonic plates results in active orogeny, and the geological conditions are fragile and steep. Because of these geological conditions in the mountainous areas of Taiwan, landslides are prone to being triggered by heavy rainfall. Landslides threaten human lives and property. In the present study, 181 shallow landslides occurring after the 921 Earthquake of 1999 were selected as the research samples. The characteristics of shallow landslides were investigated through field investigations and data collection. The results showed that in the mountainous areas of Taiwan, shallow landslides occur mostly along hillsides with a southeast to west aspect; slope ＜50°; elevation ＜1200 m; and lithology associated with the Sanhsia Group, its equivalents, and the LuShan Formation. In addition, shallow landslides are primarily induced by rainfall. These results are valuable references for formulating disaster mitigation policies and reducing potential loss of life and property damage. Moreover, the relationship between the area and volume of shallow landslides was investigated, and a log-linear formula that predicts the volume of shallow landslides based on the landslide area was proposed. This formula is valuable for quickly assessing the volume of shallow landslides during project planning.

並列關鍵字

Shallow landslide ； landslide character ； landslide volume