Types of Sliding Surface of Shallow Landslides - A Case of Ai-Liao River

• Main Authors: Yen, Hung-Yu, 顏宏諭
• Other Authors: Chen, Tien-Chien
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/ng5cmj

碩士 === 國立屏東科技大學 === 水土保持系所 === 102 === This study focuses on interpretation and classification of the shallow landslide plane and relating characteristics in Ai-Liao-Shi catchment. Landslide inventory of 2009 Typhoon Morakot and the DEM and aero photo have been interpreted by GIS software to assess the depth and scale of sliding surface. The verification of interpretation result is carried out by field investigation. The research database contents 276 landslides in which the area is smaller than 1 ha. The sliding surface is identified by field reconnaissance or aero photo removed the residual rock mass upper the slip plane. Types of sliding surface classified into translational, rotational, and log spiral plane forms and furthermore related to slope types and topographic characters. Classification of sliding surface yields that the translational plane occurred mainly in dip slope. Three forms of plane appeared uniformly in orthoclinal of dip slope. Moreover, the rotational plane occurred mainly in escarpment slope and orthoclinal of escarpment slope. Relating to the landslide location, ridge, hillside, and foot, the translational plane occurred mainly in all location in dip slope case. In orthoclinal of dip slope case, the log spiral plane occurred mainly in ridge; the rotational plane occurred most in hillside; the translational plane occurred mainly in foot. Next, in escarpment slope case, the rotational plane occurred mainly in ridge, the log spiral plane and rotational plane are roughly same amount in both of hillside and foot. Last, in orthoclinal of escarpment slope case, the rotational plane occurred most in all location. For the shape of slope, convex, straight, and concave, the translational plane occurred mainly in three kinds of shape in dip slope case. In orthoclinal of dip slope case, the translational plane occurred mainly in convex slope; the log spiral plane occurred most in straight slope; the rotational plane occurred mainly in concave slope. In escarpment slope case, the rotational plane occurred mainly in convex slope, and the log spiral plane occurred mainly in both of straight and concave slope. Last, in orthoclinal of escarpment slope case, the rotational plane occurred mainly in both of convex and concave slopes, and the translational plane occurred mainly in straight slope. The maximum depth of sliding surface is explored through the type of slope and sliding surface. Results demonstrate that the average max. depth, Davm, of dip slope is 4.6m, Davm of orthoclinal of escarpment slope is 6.3, and Davm of dip slope and orthoclinal of dip slope is between in aforementioned two slopes. In general, in dip slope and orthoclinal slopes, Davm of log spiral sliding surface is the deepest, then the rotational plane and translational plane one. Oppositely, in escarpment slope case, Davm of rotational plane is only slight deeper than the one of log spiral plane. At last, we developed an identification flow chart to predict the possible type of the sliding surface from the orientation, slope types and topographic parameters. And empirical formulas are provided to estimate Davm from the slope angle in each slope type.