淺層崩塌滑動面型態-以隘寮溪流域為例

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

顏宏諭(Hung-Yu Yen)

指導教授 ： 陳天健

國立屏東科技大學/工學院/水土保持系所/碩士(2014年)

https://doi.org/10.6346/NPUST.2014.00256

摘要

本研究主題為進行崩塌滑動面之形狀判釋及分類，選以隘寮溪流域之莫拉克風災淺層崩塌為研究對象，利用GIS配合災前後數值地形模型與航空影像作為產製及分析工具，針對淺層崩塌之滑動面形狀進行因子與分類法研究。崩塌事件選以投影面積小於一公頃之崩塌地，共計276筆。
有別於一般採用災前後DEM相減所獲得之滑動體表面。每一崩塌滑動面均依現地調查或航照影像成果，細緻剔除崩塌區上之殘積土體，求得崩塌體實際滑動面。綜合歸納崩塌滑動面形狀後，其可分為平面型、圓弧型、對數螺旋型三種滑動面。此外，本研究進一步比較順向、順斜、逆向、逆斜四種邊坡類型上滑動型態之差異，同時探討崩塌滑動面深度、規模與地形之特性。
研究結果顯示，順向坡以平面型滑動面為主；逆向坡及逆斜坡則均以圓弧型為主；而順斜坡上三種滑動面形狀之出現比率則相當。其次，就崩塌所在之山脊、坡腹、坡腳等區位分析結果顯示，順向坡崩塌區在上述三區位均以平面型滑動面為主；順斜坡之崩塌，在山脊處以對數螺旋型發生率較多；在坡腹處多為圓弧型；坡腳處則為平面型。逆向坡之崩塌，在山脊處以圓弧型為主；坡腹及坡腳處則圓弧型與對數螺旋型發生率相當。最後，逆斜坡之崩塌在三區位處，則均以圓弧型為主。而就崩塌所在之邊坡坡形如凸坡、直坡、凹坡等分析結果顯示，上述三坡形均以平面型滑動面為主；順斜坡之崩塌，凸坡以平面型略高、直坡以對
數螺旋型略高、凹坡以圓弧型略高；逆向坡之崩塌，凸坡以圓弧型為主；直坡與凹坡均以對數螺旋型為主；逆斜坡中，凸坡及凹坡均以圓弧型為主、直坡以平面型為主。
本研究亦進行滑動面之最大深度分析，結果顯示順向坡滑動面最大深度平均為4.6m，逆斜坡則為6.3m，其他兩者則介於前二深度之間。若就滑動面形狀而言，順向、順斜及逆斜坡三者崩塌地之最大滑動深度均為對數螺旋型>圓弧形>平面型；逆向坡則是圓弧形略大於對數螺旋型。本文亦進一步建立滑動面深度與垂直深度之關係式，結果獲得相當好之對應關係，可茲GIS與力學分析時，不同定義滑動深度間之轉換。
最後，本研究採用位態、地形趨勢及邊坡類型等做為區分因子，建立一套滑動面形狀判釋模式。並利用坡度與滑動面深度之關係，求得其相關公式，爾後可藉由坡度來推估滑動面深度。

關鍵字

淺層崩塌 ； 滑動面 ； 判釋模式 ； 滑動面深度 ； 隘寮溪流域

並列摘要

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.

並列關鍵字

Shallow landslide ； sliding surface ； interpretation model ； depth of sliding surface ； Ai-Liao-Shi catchment

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