Investigating the seismic ground-motion response on hillslope

• Main Authors: Yang, Tung, 楊棟
• Other Authors: Chao, Wei-An
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/phsc79

碩士 === 國立交通大學 === 土木工程系所 === 107 === Earthquake forcing is a crucial trigger factor for landslides. Thus, studying the seismic ground-motion response on hillslope is needed to understand the high potential failure area. However, the ground-motion response of hillslope is more complicated than that of plain areas, and may be affected by topography, subsurface structure and materials, and linear geological structure on surface. In this study, a site of the landslide geological sensitive area is used to study local seismic response. In order to analyze the ground-motion response of the hillslopes, the site-reference-spectral-ratio (SRSR) method was adopted, which could remove the effects of earthquake source and wave propagation path. Therefore, it can be effectively used to study site effects and terrain effects. The seismic records generated by the earthquake events during the period of July 2017 to December 2018 was collected to calculate the SRSR for each station. The result of SRSR is dominated by the site effect and/or regional topographical features, and the SRSR value represents the intensity of seismic ground-motion response. Furthermore, this study explores the effects of several factors (such as epicentral distance, azimuth of event-to-site, focal depth and temporal changes) on resulting SRSR. Our aim is to find out the criteria in successfully adopting the SRSR analysis. In this study, the maximum distance (Sd) between the station and the reference station is 1.26 km. Quality value (Q) could be computed by a ratio between earthquake-to-site distance (Ed) and Sd. This study demonstrated that the Q value should be larger than 20 for extracting stable SRSR result. The azimuth of event-to-site would influence the SRSR result, especially for earthquake events located on the east and west sides. Whereas, there is no obvious changes in SRSR results when the focal depth of earthquake ranges from 0 to 50 km. During the monitoring period of this study, the results of SRSR analysis do not exhibit the pattern of temporal change. This study concluded that the SRSR method would be helpful to comprehensively map the high potential failure area on hillslope.