2017-01-012024-05-14https://scholars.lib.ntu.edu.tw/handle/123456789/660854摘要：0206美濃地震顯示土壤液化對人類生命財產安全仍是一大威脅。在土壤液化後所遭遇的災害往往有地表下陷、建物下沉、傾斜與維生管線等受損。目前較無明確的解決模式，因此本研究擬提出對應之研究方法，期望能提供學界研究與工程設計與政府單位在相關災害防治上作為參考之用。在水平地盤沉陷量計算上，目前工程界多採用Ishihara針對乾淨砂作試驗後所得之經驗關係式，但在台灣的發生土壤液化的砂土往往都是高細顆粒含量之土壤，因此在討論土壤因土壤液化所生成之沉陷量的基礎理論與試驗以及結果上和乾淨砂的反應會相差甚大，因此本計畫首先將針對平面地盤的土壤液化引致沉陷量進行一連串的試驗與分析討論。而基礎若位於可液化之飽和砂土上，上部結構體因液化而產生的沈陷的評估方法至今為數值分析計算為多，惟其應用在工程設計上有其一定的複雜性。因此本研究擬簡化計算方法，考慮結構物在液化土層中各種力的平衡關係，推導出沈陷速率與時間的關係。故計畫中將運用數值分析程式以反算法，推估出在各種土壤條件與地震波條件下之液化土黏度值。一旦管線因土壤液化造成損害進而可能引起後續巨大的影響，因此，我們將平面地層與淺基礎建物在受土壤液化後之沉陷量納入維生管線之風險評估中。<br> Abstract: The 2016 Meinung earthquake demonstrated that the earthquake-induced soil liquefaction remains a threat to human’s properties and lives. Regarding the liquefaction potential assessments, there are several methods, e.g. SPT-N based and CPT based methods, with good degrees of accuracies. However, the liquefaction induced level ground settlement, settlement of building with shallow foundation, as well as the underground/buried pipeline failure due to differential settlement of the ground have been less studied due to their higher uncertainties. In this proposed studies, we aim to provide a comprehensive and systematic approach for engineers and government officials to deal with this type of earthquake hazards. The estimation of liquefaction induced level ground settlement has been primarily adopting Ishihara’s framework, which was based on pure sand. Although they have been working on silty sand, their work has not reached a firm conclusion and refinements are needed. Silty sand, especially with higher amount of fines content (>30%) has been identified in the liquefaction in Taiwan in recent years. Therefore, in this proposed research, we will carry out a series of cyclic triaxial tests with post liquefaction volumetric strain measurements to develop a level ground settlement framework for silty sand. Structures with shallow foundation have been found settled or tilted if they were built in a liquefiable ground. This type of failure is very difficult to quantify as so many factors involved in this process. In this proposed research, we adopt a framework considering the building to be sinking in a liquefied soil deposit. The rate and amount of building settlement depends upon the size and weight of the structure, during and intensity of the earthquake, as well as the apparent viscosity of the liquefied soil. We will carry out an extensive numerical analyses with constitutive model parameters being calibrated with cyclic triaxial tests. The results of the numerical analyses will be compared with field measurement in Shi Din area of Anan district in Tainan. With all, a chart of viscosity of soil under various conditions will be proposed for predicting building settlement. Lastly, the liquefaction induced level ground and structure settlements could lead to a differential settlement that causes a failure of the underground/buried pipeline. We will also perform a comprehensive study in quantifying the failure probability due to the differential settlement and the consequences of the failure. Furthermore, we can provide a risk assessment and management tool as well as a risk map for the area of interest.土壤液化沉陷量風險評估Soil liquefactionSettlementRisk assessment