黄河水下三角洲液化与未液化粉土的工程地质性质对比研究

Comparative Study on the Difference of Engineering Geological Characteristics Between Liquefied Silt and Non-liquefied Silt in the Yellow River Delta

以黄河水下三角洲埕岛海域海底粉土为研究对象,分析液化后重新固结粉土与未发生过液化粉土的工程地质性质差异,从浅地层剖面影像、土体的静力学参数、动力学参数、微结构特征等方面对比论述二者的不同,从而分析液化对粉土工程地质性质的改造作用。研究结果表明,粉土液化后层理结构消失,土体的主要静力学参数及动力学参数均增大,微结构特征表现为面孔隙比、圆形度及分形维数均减小,总体上土体液化固结后工程地质性质提高,若使液化过的粉土再次发生液化,需要更大的外动力条件才能实现。由于液化后粉土层理结构改变,细粒物质析出,颗粒重新排列,形成更加稳定的结构,从而强度随之增大。

This study focused on the silt soil in the Yellow River delta, and analyzed the differences in engineering geological properties between liquefied silt and non-liquefied silt. In order to understand the effect of liquefaction on the engineering geological properties of silt, we indicated the the differences in shallow profile images, soil statics parameters, dynamic parameters and microstructure features. We found that the bedding structure of silt disappeared, the main static and dynamic parameters of soil increased,and the microstructural characteristics such as the surface void ratio, roundness and fractal dimension all decreased after liquefaction. The engineering geological properties of silt were improved. And, if the liquefied silt needs to be re-liquefied again, one must exert more external dynamic conditions than before. Due to the change of silt stratification structure after liquefaction, those fine particles are precipitated and then rearranged to form a more stable structure, which will increase the strength of silt.