电极反转对电渗加固效果的试验研究

Experimental research on effect of polarity reversal to electro-osmotic

采用自制模型箱,针对杭州软黏土进行一维电渗试验来探讨电极反转对电渗加固的影响.根据反转周期将试验分为4组:1、5、15h、不反转.观察不同反转周期下电渗的特点,并与常规电渗效果进行对比,进而探讨电极反转的有效性.定期测量试验过程中的电流和排水量,计算土体电阻和界面电阻随时间的变化;并给出试验结束时的含水量、抗剪强度空间分布图.试验过程中发现,每次反转电极,电流均呈现略微上升之后又迅速降低,同时排水不会马上继续而需要等待时间,这使得电极反转组的排水效果要较常规电渗差.试验结果表明:电极反转虽然使得土体固结变形较为均匀,但是平均抗剪强度却较常规电渗差;反转周期越短,效果越差,其主要原因是电极反转会导致界面电阻急剧增大,电流降低过快,从而影响电渗效率.

A series of one-dimensional electro-osmotic laboratory tests on Hangzhou soft clay were conducted in a self-made tank to investigate the efficiency of polarity reversal. In order to compare the differences between normal electro-osmotic and adoption of polarity reversal technique, and to find out the way how reversal frequency affects electro-osmotic, four different reversal frequencies were included： 1 h, 5 h, 15 h, no reversal. Current density and drainage were monitored at set intervals during the test, and the distri- butions of shear strength, and water content as well as the variation of soil resistance and contact resist- ance with time were analyzed. Results show that the current rises slightly then reduces sharply after every time of polarity reversal, moreover, the new cathode needs a waiting time to dewatering, which leads to lower drainage than that of normal electro-osmosis; although the polarity reversal technique contributes to the uniformity of soil properties and deformation, it is not superior to normal electro-osmotic because of the worse results about shear strength; in addition, the higher frequency adopted, the worse result dis- plays. The main reason for these results is that this technique leads to the rapid rise in contact resistances, which reduces the current and finally slows the efficiency of electro-osmotic down.