震后击实黄土和原状黄土的液化试验研究

Experimental Study on Liquefaction of Post-earthquake Compacted Loess and Intact Loess

在饱和黄土动三轴试验的基础上,结合黄土微观结构特征研究和粒度组成分析,讨论了等效循环荷载作用下震后击实黄土和原状黄土的孔压比—应变关系,并从微观结构特征参数和粒度组成方面阐述了黄土孔压发展规律差异的原因.试验结果表明:击实黄土在液化过程中孔压发展较原状黄土慢,主要原因在于原状黄土大中孔隙较击实黄土含量多;震后黄土的粘粒含量较震前均有一定程度的增加,粉粒相应减少,砂粒变化较小,液化应力比随着粘粒含量的增加而增大,抗液化能力降低.

Based on the research on dynamic tri-axial test of saturated loess, combining with the analysis of SEM raicro-fabric scanning and grain size composition, this paper discusses the relation between pore water pressure ratio and strain of post-earthquake compacted loess and intact loess under cyclic viberation load, and analyzes the reasons for differences in the development regulation based on micro-structure characteris- tic parameters and grain size composition. The experimental results indicate that the pore water pressure of compacted loess increases more slowly than that of intact loess, mainly because the large and medium pore content of intact loess is much more than that of compacted loess. After the earthquake, clay content in- creases to some extent, and silt content reduces accordingly and sand content changes little. With the in- crease of clay content, liquefaction stress ratio will increase while liquefaction resistance will decrease.