万大溪河岸边坡崩塌与河道变迁之案例分析ACase-水土保持学系.PDF

萬大溪河岸邊坡崩塌與河道變遷之案例分析 (1*) (2) 馮正一 陳世旻 摘 要 本研究採用地面型3D 雷射掃描技術，量測河岸崩塌地之點雲資料，呈現崩塌地表面三維 地形，評估地形變遷。本研究於奧萬大森林遊樂區聯外道路 1.7Km 處之河岸崩塌處，分別於辛 樂克(2008) 、薔蜜(2008)颱風過境後的2009 年2 月 16 日及莫拉克(2009)颱風過後的2010 年 5 月17 日進行3D 掃描，探討崩塌地地形變化量、崩塌機制與崩塌地對河道的影響。本研究使用 點雲資料計算出露之岩石邊坡弱面之位態，並與坡趾附近區位之弱面位態現地量測結果比較發 現，邊坡出露之岩石弱面傾向與邊坡滑動面方向一致，可釋為崩塌促崩機制之一。本研究亦探 討河道凹岸受河水侵蝕作用，及因崩積材料堆積於河道上，造成河流通水斷面積縮減，而迫使 流心移動、擺盪，危及萬大溪右岸道路之安全。 關鍵字：( 崩塌地、3D雷射掃描、河道侵蝕 ) A Case Study of Wan-Da Riverbank Landslide and Channel Changes Zheng-yi Feng(1*) Shih-min Chen(2) Associate Professor(1) , Master(2) Department of Soil and Water Conservation, National Chung-Hsing University, Taiwan ABSTRACT A 3D Terrestrial Laser Scanning (3D TLS) technique was applied to measure “point cloud” of a riverbank landslide for demonstration of the 3D topography and evaluation of its changes. After Typhoons Sinlaku and Jangmi in 2008 and Morakot in 2009, we carried out two 3D TLS on Feb. 16 2009 and May 17 2010 at the 1.7 km of the connection road of Wan-da recreational park to discuss changes of the landslide, landslide mechanism, and the influence of the landslide on the river channel. The point cloud data was used to calculate attitude of the exposed weak plane of the rock slope. The attitudes of the exposed weak plane outcrop are consistent with the attitudes manually measured around the toe in the field. This can be one of the explanations of the landslide mechanisms. This study also discussed the river bank eroded by the stream water, cross-section reduction by (1)國立中興大學 水土保持學系 副教授 ( 通訊作者 e-mail ：tonyfeng @ .tw ) (2)國立中興大學 水土保持學系 研究生