| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 92 === Taiwan locates in the circum-Pacific zone with frequent earthquake activities, incessant cultivation and relentless exploration of the mountain areas, thus the analysis of the seismic slope stability becomes a significant issue. The Chi-Chi Earthquake in 1999 caused catastrophic damages to the slopes of the mountainous areas in central Taiwan, which threatened residents’ lives and caused adverse effects on traffic and economy. The direct and indirect losses associated with this earthquake are huge. Therefore, advanced research in analyzing slope under seismic loading is required. Among the various methods used to analyze the seismic slope stability, sliding block analysis is a simple and convenient way that not only describes the behaviors of seismic slopes but also can be used to evaluate seismic slope stability in large regions.
In this paper, simple-slopes with uniform soil properties and log-spiral failure surface method (Huang, 2003) are used to locate the failure surface and obtain the toe displacement. In addition, the suitable conditions which this method is applicable will be defined. In order to identity the proper land slide cases, satellite pictures, aerial photos, and reports from site reconnaissance will be used. Also, GIS software ‘ArcView’ will be used to extract data such as the failure slope angle, slope aspect and soil properties, etc. With the Chi-Chi earthquake acceleration record, log-spiral failure method can be used to calculate the slope displacement under earthquake loading and stability of slope can be evaluated accordingly.
The results from this research indicate that the critical displacements of most landslides are more than 10 centimeter while only a few cases are with 5 to 10 centimeter displacement. Therefore, it is suggested that 10 centimeters is the critical displacement where the failure of slope initiates. In addition, from the analysis results, the proper slope angle for using log-spiral failure surfaces method is 20 to 45 degree. In conclusion , slope angle is considered as the most important factor of the yield acceleration of slopes.
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