电渗作用下软土细观孔隙结构

陶燕丽　龚晓南　周建　罗战友　祝行

摘要：

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。

关键词：电渗法；细观孔隙结构；孔隙比；电渗排水量；土体收缩量

中图分类号：TU411

文献标志码：A文章编号：16744764（2018）03011007

Abstract：

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 electroosmosis， some electroosmotic 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 rearranged into sheetpacked structure with planeplane 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 electroosmotic dewatering was larger than compression amount of soil. The fundamental cause goes to the fact that electroosmosis derives from the migration of water dragged by ions and fails to generate compression of the soil skeleton directly. Electroosmosis is recommended to be combined with surcharge and vacuum preloading in real practice.

Keywords：

electroosmosis； mesoscopic pore structure； void ratio； electroosmotic dewatering； compression amount of soil

經济的飞速发展使得土地资源短缺日趋严重，围海造陆工程因此得以蓬勃发展，但由此产生大量吹填土或疏浚土堆积形成软土地基亟需有效处理。传统地基处理方法，如堆载预压或真空预压，受限于软土的水力渗透系数，往往难以达到预期目标，所以，寻求有效的新工艺或新方法对于围海造陆工程的顺利开展具有重大意义。电渗法通过在插入土体的电极上通电，加速土体排水固结，被认为是处理高含水量、低渗透性软土地基很有效的方法[14]。研究电渗法对吹填土或疏浚土等软土的加固作用成为热点之一[57]。……