电渗作用下软土细观孔隙结构

软土细观孔隙结构变化是其宏观变形的根本原因。为了探索电渗中软土细观孔隙结构变化以及与宏观变形之间的关联机制,采用杭州软土开展电渗试验,监测了电渗中土体孔隙结构分布特征和含水量,从定性和定量两个方面对试验结果进行分析。研究发现,电渗过程中,粘土颗粒重新排列形成面面接触的片堆结构,土体孔隙比降低,孔隙空间形态变光滑,结构复杂性减弱。通过含水量计算所得孔隙比较实测孔隙比小,说明电渗排水量大于土体收缩量,这是因为,电渗本质为离子带动水分子的迁移,不能直接引起土骨架压缩。实际工程中,电渗法应与堆载、真空预压等联合使用。

Mesoscopic pore structure of soft soil during electro-osmosis

Variation of mesoscopic pore structure for soft soils is the primary cause of the macroscopical deformation.In order to study the variation of mesoscopic pore structure of soft soil as well as the correlative mechanism with macroscopical deformation during electro-osmosis,some electro-osmotic experiments were performed using Hangzhou soft soils.Pore structure distribution features and water contents of the soils were monitored during the experiments.The results were explained from the qualitative and quantitative perspectives.Clay particles were re-arranged into sheet-packed structure with plane-plane surfaces.The soil pore contracted,with resulted to decreasing of the void ratio,meanwhile the pores turned smoother in spatial forms and less complex in structure.Moreover,void ratios of the soil were computed through water content and the results were smaller than the measured values,which illustrated the electro-osmotic dewatering was larger than compression amount of soil.The fundamental cause goes to the fact that electro-osmosis derives from the migration of water dragged by ions and fails to generate compression of the soil skeleton directly.Electro-osmosis is recommended to be combined with surcharge and vacuum preloading in real practice.