以微型錐貫入試驗評估不同細料含量貓羅溪土壤之液化強度

Abstract

摘要 本研究採用南投市貓羅溪岸土壤為土樣，準備不同細料含量之試體，以微型電子式貫入錐在自行設計之試驗圓槽中進行K0狀態下飽和土壤之圓錐貫入試驗。同時以CKC動力三軸儀求取不同細料含量土壤之液化強度，探討貓羅溪岸土壤細料含量對於圓錐貫入阻抗與套筒摩擦阻抗之影響及其與土壤液化強度之間的關係。 根據試驗結果，若控制試體乾密度與其所受垂直向有效應力相同時， 隨著細料含量的增加，正規化圓錐貫入阻抗會呈現下降之趨勢。由此推測CPT液化潛能評估法中對圓錐貫入阻抗所做細料含量的修正，是因為隨著細料含量的增加正規化圓錐貫入阻抗會下降，而液化強度並無太大改變的緣故。 本研究亦評估目前常用之CPT液化潛能評估法對本試驗結果之適合性，但結果並不理想。探討其中原因，除了這些評估法大都根據國外液化案例資料，經統計分析而得，對於本土高細料含量土壤之適用性有待更進一步確認外，主要是這些方法對細料含量的修正皆有其不完善之處。

Abstract This study conducted mini-cone penetration test under K0 condition in a self-designed chamber with saturated Maoluo River sand samples of different fines content. The liquefaction resistances of soils with different fines content were also obtained using the CKC cyclic triaxial test apparatus. The effect of fines content on cone penetration resistance and sleeve friction resistance was studied and the relationship between cone penetration resistance, sleeve friction resistance and the liquefaction resistance of the soil was also evaluated. According to the test results, normalized cone penetration resistance decreased with increasing fines content for soils of the same dry density and the vertical effective stress. Hence, we speculated the reason of fines content adjustment for cone penetration resistance in CPT-based liquefaction potential evaluation method was because the small liquefaction resistance changes while a more significant normalized cone penetration resistance decreasing with increasing fines content. This study also shows the commonly used CPT-based liquefaction potential evaluation methods do not give good agreement with the findings in this study. The main reason is that that these methods do not have the suitable fines content adjustment for the local soils with high fines content in Taiwan.