摘要
本研究探討南投市貓羅溪地區第二高速公路高架橋下及工務所附近之高細粒料含量土壤之組成與液化特性。由其粒徑分佈曲線得知，此兩處土壤過200號篩百分比分別為74%與48%，在統一土壤分類法(USCS)中，橋下土樣屬於CL，工務所土樣則為SM。但從粗粒料與細粒料兩部份各自特性的分析結果，可知兩處土樣為同一種土壤，且土壤礦物組成含量上大都是石英居多。 本研究利用現地土樣重模成中空圓柱形試體進行扭剪試驗，控制試體壓密後之乾密度，求取現地土壤之抗液化強度，由試驗結果所得抗液化曲線顯示，橋下土樣(FC=74%)抗液化強度比工務所(FC=48%)高，且兩者曲線近乎呈平行。 依本研究結果與陳界文之動態三軸試驗結果之比較，動態三軸試驗反覆應力比與中空圓柱形試體扭剪試驗反覆應力比之間的修正係數為Cr=0.666，與De Alba et al.(1975)所建議的修正係數相近。並且從工務所土樣細粒料含量為74%之重模試體與橋下土樣(FC=74 %)試體兩者的液化強度曲線相近，因此本研究中空圓柱形試體扭剪試驗在試體準備與試驗操作過程，有很好的可靠度。
並列摘要
This study evaluates the liquefaction of the soils of high fines contents in the Maoluo River area of Nantou City. The particle size distribution curves indicate that the fines content of the soil taken under the viaduct of the second freeway is 74% while that taken near the construction office is 48%. According to the USCS, the under-viaduct soil is CL while the soil near the construction office is SM. But based on the result of analyzing the characteristics of the granular materials and the fines, they are the same kind of soil and contain quartz mostly. In this study, the soils taken from the sites are used to make the hollow cylinder specimens for the torsional shear tests by controlling the dry density of specimens after consolidation. The test results show that the liquefaction resistance of the under-viaduct soil (FC=74%) is higher than that near the construction office (FC=48%), but the relations of the two soils are almost parallel. Comparison between this study and the previous test results by Chen shows that the correction coefficient Cr between the cyclic stress ratio of cyclic triaxial test and cyclic hollow cylinder torsional shear test is 0.666 which is very closed to the correction coefficient computed according to De Alba et al. (1975) suggested method. Therefore, the sample preparation and testing process of the hollow cylinder torsional shear test in this study is reliable. With the same fines content at 74%, the liquefaction strengths are very much the same for specimens taken under viaduct and near the construction office.