梨山地滑區排水成效之探討

Effectiveness of Drainage in Lishan Landslide Area

詹連昌(Lien-Chang Chan)

《坡地防災學報》 2卷1期 (2003/09) Pp. 1-12

https://doi.org/10.29995/JSHR.200309.0001

摘要

梨山地滑區過去曾發生大規模地盤滑動，整區面積230公頃，呈三角形，其地質主要是由崩積層及破碎板岩所組成，地滑區可分成西區、東南Ⅰ區、東南Ⅱ區及東北四個區域，每個地滑區由數個上下相關連之滑動體所構成，其長寬近百公尺或數百公尺，滑動面深度在地表下30~60公尺內，屬於大面積之深層地盤滑動。由調查與監測結果發現，其上方覆蓋之崩積層及風化板岩層透水性佳，地表水易入滲而使地下水位上升，降低邊坡之穩定性。因此降雨時引起地下水位上升，推測為造成本區地滑災害的主要誘因。目前之整治方式為施以地表排水、橫向集水管、集水井、排水廊道等整治工程。本文針對現況及施工整治成果進行檢討與評估，並配合相關之研究成果來評定使用工程方法的成效。

關鍵字

滑動體 ； 地下水位 ； 地表排水 ； 橫向集水管 ； 集水井 ； 排水廊道

並列摘要

Lishan area has experienced several large scale landslide events. The total area is about 230 ha and is triangular in shape. Alluvial layer and slate are the two major geologic consistent in this area. The landslide area can be segregated into four regions namely, West, Southeast Ⅰ, Southeast Ⅱ, and Northeast. Each region consists of several top and bottom connected sliding bodies. Its length and width is close to 100 m and often exceeds several 100 m. The depth reaches around 20 to 60 m underground and classifies as large-scale deep landslide. On-site survey and study results indicate that infiltration is good with surface-mulched alluvial layer and highly weathered slate. The percolated surface water raises the groundwater level and reduces the slope stability. This phenomenon is, therefore, speculated as the major cause of landslide disasters in this area. The current treatment method is to introduce engineering practices such as surface drainage, Horizontal drains, Drain well, and Drainage tunnel. This paper attempts to assess the treatment results of these engineering practices and to judge the effectiveness of these engineering measures with other related research findings.

並列關鍵字

Landslide ； Groundwater level ； Surface drainage ； Horizontal drains ； Drain well ； Drainage tunnel