极细颗粒黏土渗流的微电场效应试验分析

Experiment Analysis of Micro-electric Field Effects on Seepage in Micro-particle Clays

土颗粒表面附有电荷并产生微电场,电场的作用使颗粒表面形成结合水膜,同时又影响土孔隙水中的离子运动规律而产生渗流离子效应,这两方面的影响将显著改变土体微孔隙的渗流特性,上述原因产生的渗流特性变化称为渗流的微电场效应。对于极细颗粒黏土,土颗粒表面电位可达数十至数百mV,致使渗流规律受到颗粒表面电场的显著影响。采用试验方法分析极细颗粒黏土微孔隙渗流的微电场效应问题,测试了不同孔隙水离子浓度情况的渗流固结结果,并由渗流固结试验成果推演颗粒表面电位对渗流特性的影响规律。试验结果表明,随孔隙水离子浓度的减少,颗粒表面电位增大,试样等效渗透系数和固结速度随之减少,极细颗粒黏土微孔隙渗流具有明显的微电场效应。

Electric charges existing on the clay particle surfaces induce a micro-electric field, and lead to the formation of adsorbed water on surrounding clay particles. And the micro-electric field exerts an influence on the movement pattern of ion in pore water, resulting in the ion effect of seepage in clay. The two factors above will obviously change the characteristics of seepage in micropore of clays. The change of seepage property caused by the factors mentioned above is defined as micro-electric field effect on seepage （MEFES） in clay. The electric potential on the surface of micro particles clay amounts to a few tens or hundreds of mV, and then the electric field on the particle surface greatly affect the rule of seepage. Using laboratory experiment method, MEFES in micro-particle clays is discussed in this paper. A series of seepage consolidation tests are conducted for the samples of micro-particle clays with different ion concentrations in pore water or particle surface electric potentials. The test results show that an increase in particle surface electric potential or a decrease in ion concentration will result in the decrease of equivalent permeability coefficient, consolidation rate and consolidation displacement, revealing the existence of MEFES in micro particle days.