剪切波速液化判别方法对粉砂及粉土适用性研究  

Study on applicability of VS-based liquefaction potential assessment methods for silty sands and silts

作　　者：董林[1,2] 夏坤 李少华[1,2] 杨博 DONG Lin;XIA Kun;LI Shaohua;YANG Bo(Key Laboratory of Loess Earthquake Engineering, Lanzhou Institute of Seismology, CEA, Lanzhou 730000, China;Geotechnical Disaster Prevention Engineering Technology Research Center of Gansu Province, Lanzhou 730000, China)

机构地区：[1]中国地震局兰州地震研究所黄土地震工程重点实验室,甘肃兰州730000 [2]甘肃省岩土防灾工程技术研究中心,甘肃兰州730000

出　　处：《地震工程与工程振动》2019年第2期225-232,共8页Earthquake Engineering and Engineering Dynamics

基　　金：中国地震局地震预测研究所兰州科技创新基地基本科研业务费专项(2018IESLZ03);国家自然科学基金项目(51708525,51608496)~~

摘　　要：含细粒土体相对于纯净砂在自然界中分布更为广泛,其地震液化灾害在上世纪70年代之后逐渐成为研究热点,然而关于其液化判别,一直以来都只是在砂土方法的基础上,稍作调整。本文对比了美国NCEER推荐的基于标贯试验的Seed方法和基于剪切波速试验的Andrus和Stokoe方法,以历史地震数据检验方法,结果显示剪切波速方法对含细粒土体过于保守,并且细粒含量越高,对非液化点越不可靠。通过建立两个方法3组细粒含量下液化临界曲线上的剪切波速与标贯击数相关关系,得出临界剪切波速随细粒含量增加而减小的趋势没有临界标贯击数那么迅速。剪切波速试验为小应变无损测试,对含细粒土土颗粒间胶结力较为敏感,而液化状态为大应变破坏阶段,土体胶结力基本丧失,因此对胶结较强的含细粒土体,剪切波速指标与液化难以建立唯一联系。另外,中国规范剪切波速液化判别方法存在误导,由于判别式已经用黏粒含量修正,因此,Vs0经验系数应统一只取砂土数值。Silty sands and silts are more widely distributed in nature than clean sands, and its seismic liquefaction disaster has gradually been a focus of soil liquefaction engineering since 1970s. However, about its liquefaction discrimination, it has always been a little modification based on clean sand methods. In this paper, NCEER recommended SPT-based Seed methods and V s-based Andrus and Stokoe methods are tested and compared by using earthquake case histories, results show that V s-based methods are too conservative for fines-containing soils, and the higher fines percent, the more unreliable for non-liquefaction cases. By establishing the relationship between critical V s1 and critical ( N 1) 60 for 3 fines percent critical curve of two methods, it is concluded that the trend of decrease of critical V s1 with increase of fines percent is not as fast as that trend of critical ( N 1) 60 . Shear wave velocity tests are made at small strains, and sensitive to interparticle bonding of fines-containing soils. Whereas, liquefaction are high strain and destructive phenomena, these interparticle bonding of fines-containing soils has been destroyed. Accordingly, it is difficult to establish an unique correlation between liquefaction resistance and shear wave velocity for fines-containing soils. In addition, V s-based Chinese code method is misleading, because of the discriminant has been modified by the clay content, so empirical coefficients V s0 should be taken only the value of sand.

关 键 词：含细粒土体 液化判别 剪切波速试验 标准贯入试验 适用性 

分 类 号：P315.9[天文地球—地震学] TU43[天文地球—固体地球物理学]