利用坡單元及數值模擬探討霧社地區之深層滑動

Abstract

本研究以深層滑動災害為主要研究目標，探討深層滑動運動行為趨勢與滑移影響範圍。研究流程是使用ArcGIS軟體，討論不同方法繪設之坡單元較適合描述深層滑動範圍，並將選取適合之坡單元邊界進行人工編修，觀察編修後之單元邊界與研究區內之深層滑動邊界貼合性，並以廬山北坡深層滑動為例，透過多個坡單元瞭解深層滑動之滑動趨勢。再者使用LS-RAPID三維數值模擬程式，對於廬山北坡深層滑動進行模擬，並將上述兩者分析結果進行比對，並將結果再與衛星影像判釋、地形資料等比對，確認結果之正確性。 研究發現使用集水區四坡向坡單元較適合描述深層滑動之邊界，而由於研究區內之地形受人為開發破壞嚴重，地形構造較為破碎，單元邊界需進行人為編修，透過編修後之單元邊界與深層滑動邊界貼合程度佳，使用3至10塊坡單元能表示深層滑動範圍。 廬山北坡深層滑動根據前人(陳德偉，2021)結果分為三個滑動塊體，分別為右側、中央及左側。三維數值模擬分析結果將統計三個滑移塊體之滑動方向，並隨著解算時階設置越短，模擬結果方向與坡面平均坡向統計結果越相近。採用解算時階10秒之結果及坡單元統計塊體滑移方向結果與平均坡向結果相比，除了右側塊體之結果外，其餘兩塊之結果與平均坡向結果誤差5度以內。將三維數值模擬滑移塊體單位位移分佈與影像判釋及數值地形模型相減比較，皆可發現相同位移趨勢範圍分佈與高程變化。

In Taiwan, because of the plentiful topography and geology, when the typhoon or earthquake coming, it often accompanies the nature disaster. In the research focused on the deep-seated landslides for study, discussing the moving behaviors and influence area of the deep-seated landslides. Slope units are one of way to describe the boundaries of the deep-seated landslides, and they can be created by many methods. In this research, finding slope-units mapped according to watershed four reclassified aspects fitted the boundaries of deep-seated landslides is the best, but the edges of the units all need to be modified. Using delineated unit compared to the boundaries of the deep-seated landslides, it found they fit well and the use of 3 to 10 slope units can indicate the extent of deep-seated landslides. In order to explore the behaviors and influence area of deep-seated landslides, taking Lushan deep-seated landslide for study. According to the previous study, it separated Lushan deep-seated landslide into three sliding blocks, right side, center and left side, respectively. In the research also use 3D numerical simulation method (LS-RAPID) to discuss the deep-seated landslides. Taking the orientation angle for comparing, the results of 3D numerical simulation, the results of slope units and average slope are very closed within 5 degrees of error expect the right side sliding block. By comparing the 3D numerical simulation of the displacement distribution of the sliding block units with the image interpretation and the numerical terrain model, the same displacement trend range distribution and elevation change can be found.