台南新化場址土壤液化危害度分析

Hazard Analysis of Soil Liquefaction in Sinhua, Tainan

周秉宏(Bing-Hong Zhou)

指導教授 ： 黃富國

淡江大學/工學院/水資源及環境工程學系碩士班/碩士(2020年)

https://doi.org/10.6846/TKU.2020.00118

摘要

民國105年2月6日3時57分，高雄市美濃區發生一芮氏規模(ML)6.6之淺源地震，震源深度14.6公里；在台南市新化之震度達7級，台南市之震度達5級；除了在台南永康區永大路的維冠大樓倒塌造成人員重大傷亡外，「土壤液化」（soil liquefaction）頓時成了顯學，也促成了政府加速公告土壤液化潛勢區。新化場址於歷史上曾發生多次土壤液化災害，為再液化場址之重要研究區域，北勢里噴砂處鄰近高鐵行經路線，太平里則位於新化斷層通過處，兩處於工程建設或補強上皆須注意。本研究根據鑽探之地質剖面資料以各種評估法分析液化潛能指數LPI、液化機率指數Pw與液化後地盤沉陷量St，再利用蒙地卡羅模擬構建與地震危害度諧和之震力參數，求取各損害參數之液化危害度與液化易損性曲線，分析上將相關參數之不定性與變異性納入考量，使液化評估結果更為合理。調查與分析結果顯示，新化場址土壤多數為低塑性或無塑性粉土與砂土，只要地震震度夠大、延時夠長，即容易發生土壤液化，於工程規劃與設計上應針對土壤液化之危害度與易損性謹慎評估，採取適當之因應對策，避免或降低液化震害對地盤與結構物產生可能之影響。

關鍵字

美濃地震 ； 土壤液化 ； 液化危害度 ； 易損性曲線

並列摘要

Abstract:
The Meinong earthquake occurred in southern Taiwan at 3:57 a.m. on 6 February 2016. The epicenter of the earthquake was at 22.92N and 120.54E with a focal depth of 14.6 km and magnitude 6.6 (ML). The seismic intensity was up to Level 7 and 5 in the seismological stations of Sinhua and Tainan City, respectively. It caused structural collapses and 117 fatalities in Tainan. In addition, there were many areas subject to soil liquefaction that pushes the government to announce those zones vulnerable to liquefaction in Taiwan. Soil liquefaction disasters had occurred many times in Sinhua site in the past so that it is an important area for re-liquefaction researches.
The analyses had been carried out by using deterministic method to evaluate liquefaction potential index, liquefaction probability index and settlement after liquefaction. On the other hand, hazard analysis and hazard-consistent fragility curves for soil liquefaction is constructed by Monte Carlo simulation. The uncertainties and variabilities of associated analysis parameters were 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 investigation and analysis results show that most of the soils in the Sinhua site are low-plasticity or non-plasticity silt and sandy soils. As long as the earthquake magnitude is large enough and the duration is long enough, liquefaction is most likely to happen. 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

Meinong earthquake ； liquefaction hazard ； fragility curve

參考文獻

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