英文篇名
SIMPLIFIED METHODS FOR ASSESSING LIQUEFACTION POTENTIAL OF SOILS BY USING HYPERBOLIC CYCLIC RESISTANCE CURVES
作者
黃俊鴻、楊志文、陳正興
關鍵字
雙曲線函數、液化、簡易評估法、成功率、安全係數、誤差指標
摘要
以現地貫入試驗值SPT-N,CPT-qc與震測剪力波速Vs評估土壤液化潛能之方法,稱之為簡易評估法,是工程界最常使用的液化評估方法。本研究根據以往地震之液化與非液化案例資料的整理與分析,發現以雙曲線函數迴歸判斷液化與否之臨界液化強度曲線,可以合理預測集集地震與世界上其他地震之液化與非液化案例,而雙曲線液化強度曲線法不但公式簡單,且其參數具有明顯的物理意義,建議可作為本土化的液化評估方法。利用集集地震與世界上其他地震之液化與非液化案例資料,本研究以評估方法之判定成功率與至少安全係數誤差指標為評估指標,比較雙曲線液化強度曲線法與世界上其他簡易評估法的適用性。評估結果顯示,無論是SPT-N,CPT-qc與震測Vs法,以雙曲線液化強度曲線為基礎的評估方法,皆不遜於世界上現有的其他簡易評估法,建議可供工程界參考使用。
英文摘要
To assess the liquefaction potential of soil during earthquakes, the simplified procedures by using the value of SPT-N,CPT-qc and seismic Vs are the most prevailing methods applied in the engineering practices. Basically, these methods were deduced from the worldwide data of liquefaction and non-liquefaction cases reported in the past major earthquakes. In Taiwan, large amount of liquefaction data were retrieved from the devastating Chi-Chi earthquake in 1999. Therefore, it is valuable to use the Taiwan data to evaluate the performances of those simplified methods commonly used, and to deduce an improved method, if possible, to take into account the effects of local soils. Based on investigations on all data, this paper proposed a method by using the hyperbolic functions to fit the critical cyclic resistance curves, a boundary curve for judging liquefaction or non-liquefaction, in the CSR-(N1)60, CSR-qc1N, and CSR-Vs plots, respectively. The advantage of using the hyperbolic function is that it is simple in form to have physical quantities as parameters. The performances of the Hyperbolic method along with other simplified methods are then thoroughly investigated in comparison studies. From the results of two assessment indices, the prediction success rate and the error of at-least safety factor, it is shown that the proposed Hyperbolic methods performed very well as compared to the other simplified SPT-N,CPT-qc and seismic Vs methods.