膨胀土电化学改性试验研究

An Electrochemical Modification of Expansive Soil

为了研究改善膨胀土性质的方法,同时了解膨胀土改善后的性质,通过以羟基铝溶液为电解液的电化学试验方法对膨胀土的性质进行改善,将改性后的试样土分为A区(阳极区)、C区(阴极区)和M区(中间区)3个部分,并分别对3个部分试样土以及原状土进行宏观和微观试验分析。试验数据分析得到:电化学改性后的试样土的黏粒含量减少而粉粒含量增多,比表面积和孔径减小,颗粒间连接更紧密,内摩擦角增大,同时土颗粒的持水量减少,亲水性减弱,自由膨胀率大大降低。试验结果表明:膨胀土的性质变化是由[Al13]7+的离子交换和局部p H值变化等使带电土颗粒的扩散双电层变薄、颗粒间斥力变弱导致的,试样土A,C,M区的改善效果差异是受到外加电场对双电层的影响和土体微结构的各向异性等因素造成的。

The properties of expansive soil were improved by electrochemical method with hydroxyl-aluminum solution for electrolyte.The modified soil specimens were divided into three parts:part A(anode),part C(cathode),and part M(middle).Macroscopic and microscopic tests were carried out on the three parts and natural soils.Results revealed that the clay content of modified soils decreased and the silt content increased.The specific surface area and pore size decreased,which made the contact between soil particles closer,resulting in the increase of internal friction angle.Meanwhile,the water-holding capacity of soil particles reduced,indicating that the hydrophilia weakened.Moreover,the free swell of soil samples was greatly lowered.The changes in the properties are attributed to the ion exchange of[Al 13]7+and the local pH changes which thin the diffused double layer and weaken the interparticle repulsion.In addition,the effects of improvement on the three parts were different due to the influence of the applied electric field on diffused double layer and the anisotropy of soil microstructure.