高雄市土壤液化潛勢與管線震損之危害度分析

Hazard Analysis of Soil Liquefaction and Pipeline Damage for Kaohsiung City

涂堂偉(Tang-Way Tu)

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.2020.00188

摘要

高雄市係國內重要政經發展重心，但因位處西部麓山帶南緣，又位於軟弱沖積地盤上，若發生震度夠大、延時夠長之地震，將可能發生土壤液化災害，使得人民生命財產及建物與管線安全等受到威脅與損害。本研究乃蒐集「高雄市土壤液化潛勢分析」第一、二期計畫之鑽孔，經篩選後共541筆孔位試驗與地下水位資料，分別採用確值法與機率法，以JRA(1996)法、T-Y(1983)法及Seed(2001)法等三常用簡易液化評估法，分析場址之液化潛能指數LPI、液化機率指數Pw、液化後地盤沉陷量St 及管線震損率RR等，進行液化損害及管線震損之評估，與危害度及風險分析，並再結合Towhata et al.(2016)所提出之非液化土層厚度判定方法，綜合研判高雄市之液化潛能趨勢。分析中首先採用克利金插值法(Kriging)、逐步高斯模擬法(SGS)及貝氏最大熵法(BME)等三方法進行地質統計之空間推估，繪製出高雄市液化損害參數之分布圖，及捷運沿線之液化損害潛勢。三種地質統計方法之分析結果趨勢皆大致相同，都以高雄沿海一帶及各河流流域附近區域，有較高之液化潛勢。此外，本研究也評估採用降低地下水位工法，進行土壤液化防治時之可抽水深度分析，作為研擬地下水資源管理方案之參考。最後，本研究另結合危害度及脆弱度分析，將危害度、脆弱度以二維風險矩陣結合，進行土壤液化及管線液化震損之風險評估。液化風險評估結果顯示，高屏溪流域有中度液化風險趨勢，其餘地區次之;而管線液化震損風險評估結果顯示，在管線密集處及河流流域處均有高度管線液化震損之風險趨勢，其餘地區次之。以風險的角度探討各地區可能面臨之液化與管線液化震損之受災風險，能凸顯出各地區間之相對風險程度，更有利於液化及管線液化震損防減災之整備與應變。

關鍵字

高雄市 ； 土壤液化 ； 管線震損 ； 危害度分析 ； 風險評估 ； 地質統計

並列摘要

Kaohsiung is a political and economic center in South Taiwan. However, it is located in the alluvial fan area vulnerable to soil liquefaction. Thus, it is necessary to evaluate the liquefaction potential and associated hazard and risk for pipeline damage.
This research collected 541 borehole data from the first phase and the second phase of the “Soil Liquefaction Potential Analysis for Kaohsiung City” projects. Three commonly used simplified procedures, including JRA(1996), T-Y(1983) and Seed(2001) methods, are adopted for deterministic and probabilistic analysis to evaluate soil liquefaction potential and hazard and risk for pipeline damage. In addition, the method proposed by Towhata et al.(2016) is also incorporated into the analysis, from which the non-liquefaction soil thickness is taken into account to evaluate the liquefaction potential of Kaohsiung City.
In the analyses, three geostatistical methods of Kriging, SGS and BME for mapping liquefaction damage parameters (LPI, Pw and St) are employed. The variation of liquefaction damage along the MRT in Kaohsiung City is also assessed. It is shown that the coastal area and the vicinity of the river basins appear to have higher potential of liquefaction. In addition, pumpable depth of water table by dewatering to prevent soil liquefaction is also evaluated. Finally, risk analyses are accomplished by integrating the results of hazard and vulnerability for liquefaction and pipeline damage. It shows that the Gaoping River basin has a medium risk of liquefaction. As to risk of pipeline damage, the assessment indicates that there is a tendency of high risk level in river basins and areas with high pipeline density. From this research, it will provide a guideline that government can follow to take appropriate measures to reduce the damage hazard and risk of infrastructure when soil liquefaction is expected to happen.

並列關鍵字

Kaohsiung City ； Soil liquefaction ； Pipeline damage ； Hazard analysis ； Risk evaluation ； Geostatistics

參考文獻

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