【摘要】 以新疆巴楚—伽师Ms6.8级地震液化现场勘察和测试为基础,获取了47个场地的标准贯入试验资料,分析了现有基于标准贯入的砂土液化判别方法的适用性,提出了新的砂土液化判别公式。分析表明国内外现有基于标准贯入击数的砂土液化判别公式不适用于新疆地区,中国现有规范对此次巴楚地震非液化点判别成功率88%,但对液化场地判别成功率仅为38%,会给出明显偏于危险的结果。以新调查数据建立的砂土液化判别模型由地震烈度、实测标准贯入击数、标准贯入击数基准值、地下水位、砂土埋深等5个参数构成,其中标准贯入击数基准值以及地下水位和砂土埋深的影响系数分别采用归一化方法和本文提出的优化方法给出。与中国现有规范相比,新疆巴楚液化土层有所增加,推导出的标准贯入击数基准值远小于现有规范,表明巴楚地区抗液化能力显著低于以往形成我国规范时调查的可液化场地,深层土和低水位砂层液化可能性更大。所建立的砂土液化判别新公式,液化回判成功率为91%,非液化回判成功率为85%,表明构建的模型合理,计算公式可靠,同时新公式延续了中国现有规范的基本形式,工程使用方便,可为新疆地区区域性规范制订提供参考。更多还原

【Abstract】 The in-situ SPT data at 47 sites have been collected in the liquefaction survey of Bachu Ms 6.8 Earthquake,Xinjiang,China.The feasibility of the existing sand liquefaction evaluation methods is analyzed,and a new evaluation formula is proposed.The analysis shows that the current assessment formulae using SPT for sand liquefaction are not applicable in Xinjiang area,which will present obvious risky results.Based on new investigation data,five parameters including seismic intensity,measured SPT values,datum SPT values,water tables and depths of sandy soils are included in the new liquefaction evaluation model.The datum SPT values,the influencing coefficients of water tables and sand depths are gained by a normalized method and by an optimizing method,separately.The characteristic depths of sand are larger than those in the existing Chinese seismic design codes,and the datum SPT values are far larger than those in the code,indicating that the possibility of deep sand liquefaction under low water tables is high in Bachu Earthquake.The successful judging rates by the new formula are 86% and 88% for liquefied sites and for non-liquefied sites,respectively.The proposed new formula can be employed for site liquefaction evaluation and regional code formulation in Xinjiang area.更多还原