| Summary: | 碩士 === 國立海洋大學 === 河海工程學系 === 90 === Geosynthetic reinforced soil (GRS) retaining walls have been extensively used in recent years. Because of well performance in sustaining seismic loading, GRS retaining structures have become stepwise mainstream of design of retaining wall in many countries occurring earthquake frequently. During the magnitude 7.3 Chi-Chi earthquake that occurred in Taiwan on September 21, 1999, a large number of earth retaining structures failure were observed. These failures offer almost a unique opportunity to investigate the ultimate seismic behavior of various earth retaining structures, including the Geosynthetics reinforced soil (GRS) retaining walls that have generally performed well under seismic loading condition.
Among present GRS retaining systems, modular block faced GRS (MBF-GRS) walls have been recognized as one of the most complicated systems of which seismic performance is very difficult to analyze. In this paper, numerical modeling techniques, which simulate MBF-GRS retaining wall, that are able to perform both static and seismic analyses were developed. In an effort to analyze static and seismic performance of the studied MBF-GRS walls, numerical models were developed using the finite difference method computer program FLAC. FLAC models used in this study were modified from MBF-GRS models developed by Lee (2000). The complicated modular block facing system was simplified as a Mohr-Coulomb material element surrounded with structural cable elements to avoid instability of the many interfaces between different materials.
For static analysis, the geogrid reinforced modular block faced wall of the FHWA Algonquin test wall and three RMCC full scale test walls were reproduced. Instrumentation measurements such as wall deflection and reinforcement strain distributions of the case histories were successfully reproduced. Moreover, results of seismic performance analyses of three MBF-GRS walls in the Da-Kung Village of Taichung Country were also presented. Compared to the filed performance data, the developed numerical models were able to predict the seismic performance of the studied cases in a reasonable range. Finally, issues of seismic design of MBF-GRS walls such as reinforcement spacing and soil compaction are discussed in this paper as well. Discussions and conclusions of this paper are hoped to be of interest to the seismic design and research development of the GRS retaining structures.
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