电解减饱和法处理可液化地基的现场试验研究

电解减饱和法是近年来提出的一种处理可液化地基的新方法,通过电解饱和地基中的孔隙水生成气体,达到减小地基饱和度并提高抗液化强度的目的。采用石墨毡为电极,开展恒定电流强度下的现场电解减饱和试验研究。通过地基压缩波速试验测得电解作用下地基深部的饱和度从98.2%减小至94%。着重分析了地基土在电解过程中的电学特性,试验结果表明:等效电阻随着饱和度的减小而逐渐增大,呈现出较好的单值函数关系;随着电流强度的增大,等效电阻的增长速率越高,其电阻增幅也越快,达到最大等效电阻所消耗的电量先逐渐增大,然后再趋于平缓;虽然增大电流强度会略微增加耗电量,但是可以显著提高电解减饱和法效率。此外,等效电阻的衰减过程可以分为快速衰减、平缓衰减和稳定3个阶段,其中快速衰减阶段为停止电解3 h内,等效电阻的平均衰减速率为11Ω/h;由于试验场地位于河边,电解产生的气泡易受渗流的影响,使其难以长期维持在正负极间土层中;然而在该阶段,其电阻降幅也仅有15%,使可液化地基仍维持着较好的抗液化能力。对地基二次或多次电解,可以大幅节省耗电量,约为首次电解的30%;而且还能加快地基正负极间土层中气泡的生成量,从而有效减小饱和度,提高电解减饱和法效率以及地基的抗液化能力。

Field tests on liquefaction resistance of desaturation measure of electrolysis

The electrolytic desaturation method, as an innovative mitigation of soil liquefaction, is proposed in recent years. Liquefaction resistance can be improved by the air bubbles produced by electrolysis of the pore water inside the saturated sandy foundation. Desaturation tests are carried out under the constant current intensity with graphite used as the electrodes. Based on the compression wave velocity tests, the saturation of soil in the deep foundation is found to be reduced from 98.2 % to 94 % in the process of electrolysis. By focusing on the electrical properties of the foundation soil in the process of electrolysis, some results are obtained. Firstly, the equivalent resistance gradually increases with the decrease of saturation, which shows a good single value function. Secondly, with the increase of current intensity, the equivalent resistance of the growth rate is higher, and the resistance increases more quickly, meanwhile to achieve that the maximum power consumption of equivalent resistance increases gradually, and then tends to be gentle. During the process, a slight increase in power consumption caused by the increase of current intensity is balanced by significant improvement of the efficiency of desaturation measure of electrolysis. In addition, the attenuation process of equivalent resistance can be divided into 3 stages: rapid attenuation, smooth attenuation and stability. 3 h after cessation electrolysis is the rapid attenuation phase, and the equivalent resistance of the average decay rate is 11 Ω/h. Even though it is difficult to maintain bubbles between the electrodes in the long term due to seepage factor resulted from river test site, 15% drop of electric resistance in the rapid attenuation stage indicates that the liquefiable foundation can still maintain good liquefaction resistance. Then it can significantly save lots of power consumption by electrolyzing