基于剪切波速的砂砾土地震液化评价新方法  

Shear wave velocity-based new procedure for assessing seismic liquefaction triggering of sand-gravel soils

作　　者：陈国兴[1,2] 孙苏豫 吴琪 杭天柱[1] CHEN Guo-xing;SUN Su-yu;WU Qi;HANG Tian-zhul(Institute of Geotechnical Engineering,Nanjing Tech University,Nanjing 210009,China;Civil Engineering&Earthquake Disaster Prevention Center of Jiangsu Province,Nanjing 210009,China)

机构地区：[1]南京工业大学岩土工程研究所,江苏南京210009 [2]江苏省土木工程防震技术研究中心,江苏南京210009

出　　处：《岩土工程学报》2022年第10期1763-1771,I0003,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家重点研发计划项目(2018YFC1504301);国家自然科学基金项目(52008206)。

摘　　要：剪切波速Vs是表征土体动力特性的最基本参数之一,也是评价土壤抗地震液化能力的重要指标。通过系列弯曲元试验,探讨了含砾量Gc、相对密度Dr和初始有效围压σ’0对棱角状和亚圆状砂-砾混合料Vs的影响。结果表明:随着Gc的增大,砂-砾混合料的Vs表现出先增大后降低的趋势;以0.1 mm作为填充颗粒的界限粒径,发现基于二元介质模型的骨架结构孔隙比e与归准化剪切波速Vs/(σ’0/pa)n存在单一的负幂函数关系,n为砂–砾混合料的不均匀系数Cu的幂函数,pa=100kPa。据此,建立了砂–砾混合料剪切波速Vs与e的经验关系式,并结合文献中基于室内循环试验给出的砂–砾混合料的抗液化强度数据,提出了基于剪切波速的砂–砾混合料液化触发的临界曲线表达式。利用中国2008汶川大地震、意大利1976 Friuli地震的砂砾土场地液化数据,验证了其适用性。该液化评价新方法具有较好的工程应用价值。The shear wave velocity Vs is one of the most basic parameters for characterizing the dynamic behaviours of soils,and it is also an index for assessing the seismic liquefaction resistance of sand-gravel soils. To explore the influences of gravel content Gc, relative density Dr, and initial effective confining pressure σ’0 on Vs, a series of bending element tests are carried out on angular and subround sand-gravel mixtures with varying Gc, Dr, and σ’0. The results indicate that Vs has a trend of first increasing and then decreasing with Gc. Under the assumption that the size limit for the fillers is 0.1 mm, it is found that a virtually unique correlation of negative power function exists between the binary packing material-based skeleton void ratio eand the normalized shear wave velocity Vs/(σ ’0/pa)n, in which n is a power function of the coefficient of uniformity Cu of sand-gravel mixtures, and pa = 100 kPa. On this basis, an empirical formula for Vs and eis proposed. Based on the cyclic laboratory test data on the cyclic resistance ratio(CRR15-lab) in 15 cycles of various sand-gravel mixtures published in the literatures, a shear wave velocity-based equation for assessing the liquefaction triggering of sand-gravel mixtures is proposed. It is validated by the liquefaction data of sand-gravel soil sites during the 2008 Wenchuan great earthquake, China, and the 1976Friuli earthquake, Italy. The new procedure for assessing the liquefaction triggering of sand-gravel soils is valuable in engineering practices.

关 键 词：液化评价方法 剪切波速 砂–砾混合料 二元介质模型 

分 类 号：TU435[建筑科学—岩土工程]