| Summary: | 碩士 === 國立臺北科技大學 === 土木與防災技術研究所 === 92 === Taiwan is located at the edge between the Eurasian plate and the Philippine plate. Earthquakes happen frequently and faultlines exist everywhere. The movement of the Che-Long-Pu fault, caused the Chi-Chi earthquake with a magnitude of 7.3 on Richter scale on September 21, 1999. The disasters spread throughout Taiwan. On October 22 of the same year, Taiwan also had an earthquake with a magnitude of 6.4 on Richter scale in Jiayi. A seismograph was set-up on the dam right shoulder of Ren-Yi-Tan dam in Jiayi. The maximum ground surface acceleration was 992gal in this earthquake. It caused a number of cracks on the top of the Ren-Yi-Tan earth dam. Although it did not cause the dam to fail, it still endangered the lives and property security of the downriver inhabitants. Therefore, the reservoir administrative department should analyze the safety of the earth dam due to the earthquake and evaluate the safety management values.
When the earthquake occurs, the pore water pressures in the earth dam will react earlier than the displacements. The pore water pressure is sufficient to actively monitor as a warning signal of the earth dam failure. The total stress analysis method is used frequently, but it cannot obtain the pore water pressure in the earth dam. Therefore, we used the effective stress analysis code DIANA-SWANDYNEⅡ in this study, and matched up the geotechnical engineering centrifuge model testing of VELACS project in U.S.A. Compare the numerical analysis with the centrifuge testing results to evaluate the ability of this program. Then we used the program to simulate the buildup of the pore water pressure when the Ren-Yi-Tan dam is subjected to the cyclic loading. Finally, analyze the safety of the earth dam from future earthquakes, and evaluate the possibility of future dam failure.
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