| Summary: | 碩士 === 國立中興大學 === 水土保持學系所 === 105 === Except the shallow landsides that are associated with soils, other slope stability problems are associated with rock. The hill slopes of Taiwan are mainly composed of sedimentary rocks and metamorphic rocks. The bedding planes in the sedimentary rocks and the cleavage in the slate are weak planes with good consistency. Various orientations of these weak planes have different effects on the stability of rock slopes. We study the effects of orientations of planar and wedge weak planes on slope stability, using the software PLAXIS 3D.Simple slope model with various weak plane conditions are simulated. The jointed rock model with overall Mohr-Coulomb failure criterion (Iso-JRMC) is used to take the weak planes into account. The results show that for planar weak planes conditions, the most unfavorable conditions appear when the weak planes and the slope dip to the same direction, and the dip angle of the weak planes coincides with that of the slope or is equal to 90 °. For wedge weak planes conditions, the most unfavorable condition appear when the line of intersection of two sets of weak planes and the slope dip to the same direction, and the plunge of the line of intersection coincides with the dip of the slope or is equal to 90 ° . In particular, the higher the difference of the dip angles of the two sets of weak planes, the lower the safety factor of the slope obtained. For the studied cases, the rainfall induced rizes of groundwater tables from highest to lowest appear in the oblique slope, anaclinal slope, and dip slope.
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