304桃源地震台南新化土壤液化案例探討

Case Study on the Soil Liquefaction for the 2010/03/04 Taoyuan Earthquake

吳俊磊(Chun-Lei Wu)

指導教授 ： 黃富國

共同指導教授 ： 劉明仁(Ming-Jen Liu)

淡江大學/工學院/土木工程學系碩士班/碩士(2012年)

https://doi.org/10.6846/TKU.2012.00811

摘要

民國99年3月4日，高雄地區發生一芮氏規模(ML) 6.4 的桃源地震（原名甲仙地震），在台南新化北勢里、太平里、東榮里，以及山腳里等鹽水溪流域旁發生了多處土壤液化現象，本研究根據現地鑽探所得之地質剖面資料，利用蒙地卡羅模擬(MCS)，來建構與地震危害度諧和之液化危害度與液化易損性曲線，不但各相關分析參數之不定性與變異性，皆可納入考慮，且可以成對之震力參數(PGA, M)來同時考慮最大地表加速度PGA與地震規模M對土壤液化的效應，使得液化評估結果更為合理。根據此次土壤液化震害概況，以及調查及分析結果，可歸納下列三點結論供工程界參考：（1）只要地震震度夠大（最大地表加速度PGA 大）、強震延時夠長（地震規模M 大）高地下水位之疏鬆粉質砂土或無塑性粉土等現代沖積地層，以及砂岩之風化表層，皆有發生土壤液化之可能性。（2）過去地震時曾經發生土壤液化震害之場址，將來再度受震液化之可能性是相當高的。（3）工程規劃設計時，應針對土壤液化之易損性及危害度謹慎評估，並採取適當之因應對策，以避免或降低液化震害對地盤及結構物可能產生之影響。

關鍵字

桃源地震 ； 土壤液化 ； 液化危害度 ； 易損性曲線

並列摘要

Soil liquefaction is a common type of ground failure, such as sand boiling, settlement and lateral spreading, during an earthquake. A case study of Sinhua site next to Yen-Shui River watershed, subject to liquefaction in the 2010 Taoyuan earthquake with magnitude of 6.4 (ML) in Taiwan, is performed. A method to construct the hazard-consistent fragility curves and hazard analysis for soil liquefaction by Monte Carlo simulation is proposed in this study. The uncertainties and variabilities of associated analysis parameters are all easily included. The earthquake magnitude (M) and the associated peak ground acceleration (PGA), i.e. the pair of seismic parameter of PGA and M, can be considered simultaneously for the evaluation of liquefaction. The analysis results of liquefaction potential and damages thus obtained are more reasonable. The hazard-consistent fragility curves and hazard analysis for soil liquefaction by Monte Carlo simulation are constructed using three damage indices, including liquefaction potential index, IL, liquefaction probability index, PW, and settlement after liquefaction, St. It can be concluded that non-plastic cohesionless soils under saturated condition are susceptible to liquefaction, especially for those sites where liquefaction had occurred in past earthquakes. Thus, the effects of soil liquefaction and associated hazards should be carefully analyzed and evaluated to prevent potential damages in engineering planning and design.

並列關鍵字

Taoyuan earthquake ； soil liquefaction ； liquefaction hazard ； fragility curve

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