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Flow Characteristics of Large-Scale Liquefaction-Slip of the Loess Strata in Shibei Tableland, Guyuan City, Induced by the 1920 Haiyuan M8 1/2 Earthquake 
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下载免费PDF全文 MA Xingyu WANG Lanmin WANG Qian WANG Ping ZHONG Xiumei PU Xiaowu LIU Fuqiang XU Xiaowei 《中国地震研究》2020,34(4):469-481
Based on the dynamic triaxial liquefaction test of the loess samples which are taken from Shibei tableland, Guyuan City, Ningxia, China, the characteristics of dynamic strain, dynamic stress and pore water pressure are studied under cyclic loading. Triaxial shear test is conducted immediately after the sample reaches liquefaction point. During the test, the property of the liquefied soil is analyzed through fluid mechanics method, whereby the fluidity of the liquefied soil is represented by apparent viscosity.The results show that the fluidity of liquefied loess changes from "shear thickening" to "shear thinning" as the shear force continues, and the fluidity of liquefied loess is closely related to its structure. In addition, in the process of forming a new stable state, the apparent viscosity and deviant stress change with axial strain in a similar approach. When the sample reaches its stable state, it meanwhile shows a relatively stable apparent viscosity. According to the fluid mechanics and the law of conservation of energy, the slip distance of the liquefied soil is estimated, and the results are in good agreement with the field investigation results. 相似文献
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本研究对发育于亚热带地区花岗岩和变质岩风化壳之上的两个红壤剖面进行了系统的环境磁学测量及色度分析，探讨在同一地区不同母质上发育的红壤磁性差异的原因及其环境意义.研究区的两个剖面分别位于福建省南平市高铁北站和纺织厂附近，相距约15 km，气候条件基本相同.研究结果表明：（1）较强磁性的花岗岩母质层上发育的南平北站红壤（NPN），在发育过程因母质层中多畴（MD）颗粒磁赤铁矿化的磁铁矿溶解，剖面上部的淋溶层和淀积层虽以较细的稳定单畴（SSD）颗粒和少量的假单畴（PSD）颗粒磁铁矿为主，但剖面磁性自下而上减弱.相较而言，南纺红壤（NF）剖面发育在磁性较弱的变质砂岩上，其过渡层和母质层以赤铁矿为主，因成壤过程中生成较细的超顺磁（SP）磁铁矿使得土壤淋溶层和淀积层磁性增强；说明母质不同是亚热带地区红壤磁性差异的主要原因.（2） NPN和NF两个剖面的气候条件基本相同，磁性差异比色度指标差异更为显著.亚热带地区因剖面受母质影响显著，整体磁性特征不能反映气候；黄度和红度的比值（b*/a*）远小于磁性的差异，说明针铁矿和赤铁矿的比值更能反映研究区的平均气候状况，即反映次生磁性矿物含量的参数为更适合的气候指标. 相似文献
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