| Summary: | 碩士 === 朝陽科技大學 === 營建工程系碩士班 === 91 === Abstract
Because of steep topography, inferior geological condition and severe climate, slope instability is always a serious problem in Taiwan. Common failure modes of rock slopes are composed of planar, wedge, toppling and circular. Toppling failure always occurs in anaclinal slopes of layered rock mass, such as thin-bedded sedimentary rocks, foliated metamorphic rocks and those of one single joint set. Because its failure process is quite long, toppling has not been well noticeable in Taiwan. Among the types of slope failures, the number of damages due to rock falls and toppling failures was ranked the second during 921 earthquake. Therefore, had to understanding the failure of toppling of rock slopes.
Numerical analyses using UDEC (a program based on distinct element method) will be used to analyze two rock slopes of the toppling that on Highway 14 to understand the failure mechanisms.
The Highway 14 chosen for illustrative purpose is located in the middle part of Geologic Region, and its route is mainly covered by slate and argillite. The results of analyses using UDEC indicate that: the failure modes of rock slopes are correspond to erosion or excavate toe of slopes on case 1, and rock slopes was toppled by weathering and an overburden load on case 2. The hardness rock slopes were neither plastic deformation nor tend to toppling, that were different from weak slopes of failure modes. When Rock Bridge of length, Rock Bridge of continuity and an overburden load to increase, friction angle of joints of rock slopes to increase for stable. The results of parametric study indicate that : when Rock Bridge of length less then 4m and Rock Bridge of continuity between 30%~70%, an overburden load is effect more then Rock Bridge of length and Rock Bridge of continuity. When Rock Bridge of length greater then 6m and Rock Bridge of continuity between 30%~70%, the Rock Bridge of length and Rock Bridge of continuity is effect more then an overburden load.
Keywords: Toppling failure, UDEC, Rock Bridge, continuity, an overburden load
|
|---|
