碱污染红黏土物理性质及微观结构试验研究

碱污染使得贵州某铝厂地基红黏土孔隙比、比重和塑性指数降低。结合实际污染液浓度及入磨母液为污染源,考虑时间和浓度效应,对碱污染原状红黏土通过室内土工、电镜扫描试验、能谱分析,研究其物理性质的变化。结果表明:高浓度下,各基本物理指标总体低于蒸馏水养护下各指标,有机质含量、比重、黏粒含量、塑性指数、孔隙比整体降低,养护0~10 d期间,浓度越大指标降低程度越大,10 d时出现极值点;低浓度下,土颗粒较为分散,各物理指标多在20 d或40 d时出现极值点;入磨母液中,各物理指标均较低。污染红黏土特殊物理性质的变化是其微观孔隙面积、颗粒个数、新盐填充在微观孔隙内部以及黏土矿物吸附溶液中物质所共同导致的,另外,碱污染红黏土中粘土矿物不吸附Mg元素,岩土工程中应引起注意。

Experimental Study on Physical Properties and Microstructure of Red Clay Polluted by Alkali

The vulnerability of the foundation of a factory building in Guizhou is due to the alkali pollution,which is originated in the decrease of void ratio,specific weight,and plasticity index of the land.In order to study the transformation of fundamental physical properties of red clay,the authors designed laboratory experiments combined with the pollution of the alkali concentration and the sources of the production process of Alumina.The facts of maintenance time and concentration of alkali liquor were also considered into the experiments.Within the help of technologies such as scanning electron microscope （ SEM) and energy spectrum analysis,the results were concluded and supported by the raw data.The achieved results suggest that the organic matter,specific weight,clay content,plasticity index and the void ratio all decreased within the increase of independent variables under high NaOH solution.The numbers are lower than the null samples of red clay throughout the experiment,which is maintained in the distilled water.During the first 10 days of the experiment,the reduction of fundamental physical properties increased with the concentration of lye.The extreme value of high NaOH solution appeared to be on the tenth day.Which under the circumstances of low NaOH solution,soil particles are dispersed.The extreme value of the physical properties appeared on twentieth day and the fortieth day.The physical properties are measured at a low extent under the pure alkali concentration solution.This conclusion proposes that the dependent variables of the microstructure of red clay polluted by alkali are the pore areas,gain's numbers,the new salt accumulated in the pores of the microscopic pores and absorbed the material.In addition,clay minerals in alkali contaminated red clay do not absorb Magnesium elements,which should be noted in geotechnical engineering.