国内外地震液化场地特征对比研究

Comparative study of features of liquefied sites at home and abroad

收集整理了阪神、通海、唐山、集集以及海城地震等5次大地震的液化资料,对比分析了场地特征,剖析了其差别和联系。分析结果表明,几次地震中液化层埋藏深度、液化场地地下水位深度差异明显,液化层和地下水位分布范围从小到大依次为通海地震、唐山地震、阪神地震和集集地震,液化层分别主要集中在0～2、2～6、4～6、2～8m间,地下水位则分别主要集中在0～1、1～2、1～3、1～3m间;集集地震液化层埋深和水位均分布最广,液化层埋深分布在0～20m,地下水位则分布在0～9m范围;几次地震液化层标准贯入击数集中范围相似,主要在5～15击之间,但范围差异显著,通海地震虽然地下水位和液化层埋藏深度最浅,但标贯击数均值最大,而集集地震标贯击数范围最广,最大超过30击;几次地震液化层剪切波速变化范围差异明显,海城地震在150m/s以内,阪神地震集中在150～200m/s,而集集地震集中在150～250m/s,其均值接近200m/s,且有波速250m/s左右液化场地存在,以往认为场地剪切波速210m/s以上可不考虑场地液化的认识有误。

Liquefaction data from five major earthquakes, i.e. Kobe, Tonghai, Tangshan, Chichi and Haicheng earthquakes, are collected. The features of liquefied sites are comparatively analyzed to inspect the difference and link. The analytical results show the depths of liquefied layers and the groundwater tables in liquefied sites are obviously different. The depths of liquefied layers mainly are 0-2 m, 2-6 m, 4-6 m and 2-8 m and the groundwater tables mainly are 0-1 m, 1-2 m, 1-3 m and 1-3 m in Tonghai, Tangshan, Kobe and ChiChi earthquakes respectively. The depths of liquefied layers are located from 0 m to 20 m while the groundwater tables are from 0 m to 9 m in ChiChi earthquake, which are the largest ranges. The numbers of standard penetration test （SPT） counts from the earthquakes are similar and mostly are 5-15 counts; but the numbers in ChiChi earthquake vary the most significant with a maximum value more than 30. The average shear wave velocities of the liquefied layers in the earthquakes are considerably diverse. The shear wave velocities are less than 150 m/s in Haicheng earthquake but mainly concentrated in 150-200 m/s in Kobe earthquake. The shear wave velocities in Chichi earthquake mainly are 150-250m/s with an average value of 200 m/s. Sites with shear wave velocities more than 250 m/s liquefied, which disputes previous acquaintance that sites with shear wave velocities more than 210 m/s cannot liquefy.