Pb^(2+)污染对红黏土变形特性影响分析

Mechanism Analysis of Strain Characteristics of Red Clay Effected by Pb^(2+)

为探索重金属Pb^(2+)侵入对红黏土变形特性的影响,以广西桂林红黏土为研究对象,对受不同Pb^(2+)浓度污染的红黏土试样开展相对密度试验和固结试验。结果表明:随着Pb^(2+)浓度的增大,红黏土的相对密度增大,相应的孔隙比也会增大;固结试验结果表明:Pb^(2+)污染后红黏土的压缩系数在低浓度、低压力时比高浓度、低压力的大,这表明Pb^(2+)的侵入对减弱了红黏土抵抗变形的能力;在50 kPa下0.05 mol/L Pb^(2+)溶液污染后红黏土的压缩模量比未污染红黏土降低了67.2%。此外采用Zate电位试验并结合Gouy-Chapman扩散双电层理论得出:Pb^(2+)污染后,红黏土扩散层的电位减小,这是由于渗透压力和离子间的作用力使Pb^(2+)进入扩散层,致使其价态和浓度升高,所以红黏土扩散层厚度随着Pb^(2+)浓度的增加在不断减小。红黏土的电位值随Pb^(2+)浓度增大而减少,并且曲线逐渐趋于平缓,扩散层厚度的减小也随之趋于平缓。

To explore the effect of heavy metal Pb^(2+) intrusion on the deformation characteristics of red clay,relative density tests and consolidation tests are conducted on red clay specimens contaminated with different Pb^(2+) concentrations,the research object is the red clay of Guilin.The results show that the relative density of red clay increases with the increase of Pb^(2+) concentration and the corresponding pore ratio also increases;the results of consolidation test show that the compression coefficient of red clay after Pb^(2+) contamination is larger at low concentration and low pressure than that at high concentration and low pressure,which indicates that the invasion of Pb^(2+) weakens the ability of red clay to resist deformation;The compressive modulus of red clay after contamination with 0.05 mol/L Pb^(2+) solution at 50 kPa is reduced by 67.2%compared to uncontaminated red clay.In addition,the Zate potential test combined with the Gouy-Chapman diffusion bilayer theory shows that the potential of the red clay diffusion layer decreases after Pb^(2+) contamination,which is due to the increase in the valence and concentration of Pb^(2+) as a result of the osmotic pressure and inter-ionic forces that cause Pb^(2+) to enter the diffusion layer,so the thickness of the red clay diffusion layer is decreasing as the Pb^(2+) concentration increases.The potential value of the red clay decreases with the increase of Pb^(2+) concentration and the curve gradually flattens out,and the decrease of the diffusion layer thickness also flattens out.