| Summary: | 碩士 === 國立交通大學 === 土木工程系所 === 104 === It is important to investigate the potential for large-scale landslides for natural geo-hazard mitigation. Previous studies on this issue were majorly to identify potential landslide sites, to understand failure mechanism and to predict possible failure time. A hillslope with a potential for large-scale landslide could experience a series of geomorphological evolution in the past resulting from previous landslides and subsequent runout. Through exploring the past geomorphological evolution of a potential large-scale landslide site, it can be beneficial for a better understanding of the site condition at present, and can be helpful for predicting the potential slope failure in the future.
A site in Luchang (in Miaoli County, Taiwan) is taken as a case study for studying the geomorphological evolution of a hillslope with large-scale landslide potential. This hillslope contains obvious scarps and thick colluvium which show evident signs of large-scale landslide in the past. Starting with a comprehensive site investigation, this thesis constructs the geological model of the studied area and proposes a conceptual model of geomorphological evolution at this site. Successively, a series of slope stability analysis under various scenarios and subsequent run-out simulation are conducted to support the possibility of the conceptual model of geomorphological evolution. With an initial convex ground surface, the hillslope first experienced a couple times of large-scale plane failure and its following runout. After the scarp retreated to near the axis of anticline, the mechanism of slope failure turned from plane sliding to lasting rockfalls; talus was thus formed under the scarp. Eventually, the hillslope turned into its current landform. This study simulated the evolution process of this hillslope stage by stage. The results of the numerical simulations demonstrate that each process in the conceptual model is possible in mechanics and kinematics.
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