饱和黄土场地原位试验及液化势评价

目前,主要依靠室内动力试验对黄土液化势进行评价。由于黄土特殊的结构性,室内试验对其饱和的过程较为复杂,且与实际场地饱和黄土差异明显,导致室内黄土液化试验结果并不能代表现场饱和黄土的抗液化强度。本文选取兰州市西固区寺儿沟村某饱和黄土场地进行钻孔测试,现场实施了标准贯入试验、静力触探试验以及剪切波速测试。应用Robertson的土类指数分类图对该场地不同含水率黄土的土类进行了界定,确定了饱和黄土属于类砂土,有液化势。应用NCEER推荐方法,计算了3组原位试验数据的饱和黄土循环抗力比（CRR）,通过与1976年唐山地震和1999年集集地震液化土CRR对比,得出了饱和黄土抗液化强度很低的结论。

In-situ Tests and Liquefaction Potential Evaluation for Saturated Loess Sites

At present, liquefaction potential evaluation for loess mainly depends on laboratory dynamic test. Because of the special micro-structure, loess sample saturation process is very complicated, and the saturated loess sample is remarkably different from actual saturated loess in field. Therefore, laboratory cyclic test results can not fully represent liquefaction resistance strength of field saturated loess. This paper selects a saturated loess site in Si''ergou, Xigu district, Lanzhou City, drills a borehole, and carries out standard penetration test, cone penetration test, and shear wave velocity test. Using CPT-based soil behavior-type chart proposed by Robertson, soil behavior classification of loess with different water content was determined, and saturated loess definitely belongs to sand-like soils. Using NCEER recommended methods, cyclic resistance ratio(CRR) of saturated loess was calculated respectively from SPT, CPT, and V_S. By comparing with SPT-based and CPT-based CRR range of liquefied soils in 1976 Tangshan earthquake and 1999 Chi-Chi earthquake, we found that saturated loess is very vulnerable to liquefaction.