重金属污染对土压实性及抗剪强度影响的试验研究

EXPERIMENTAL RESEARCH ON THE EFFECT OF THE HEAVY METAL POLLUTANTS ON SOIL COMPACTNESS AND SHEAR STRENGTH

通过在实际重金属冶炼企业的尾矿库、废料堆填区采取重金属尾矿样品,与代表性净土进行掺和,配制了不同压实度、不同龄期、不同掺和比的重金属污染土样;在各自的最优含水量下,进行击实和直接剪切等物理力学试验,研究重金属污染对土的压实特性与抗剪强度的影响规律。试验表明:1)重金属污染对土体击实特性的影响,金属Mn的影响不大,Pb、Zn、Cd、Cr影响较大,后者表现为随掺和比增大,最优含水量减小,土的最大干密度增大;2)随着重金属污染土体压实度的增大,土的黏聚力C逐渐增大的,内摩擦角φ值逐渐降低,污染土的强度指标明显低于重塑净土的抗剪强度指标;3)重金属污染的作用效应是一个缓慢的过程,随着重金属污染物作用时间的延长,土的黏聚力c值下降,内摩擦角φ值上升;4)随着污染浓度的增加,土的黏聚力c值增大,则φ值呈降低趋势。

The heavy metal tailing samples were taken from tailing pond and landfill site of wastes, which were then mixed with typical uncontaiminated soil. The heavy metal contaminated samples with different incorporation ratio, different density and ages were prepared. Under their respective optimum moisture content, direct shear test and the compaction test were done in order to study the effect rules of compaction and strength shear by heavy metal pollution. The results showed： 1） Heavy metal pollution affected the compaction characteristics of soil. Mn had a weak impact on the soil. Pb,Zn,Cd, and Cr had great impacts on the soil, the maximum dry density of soil increased, optimum moisture content decreased with the different incorporation ratio increasing; 2） with the degree of consolidation increasing, c value gradually increased, φ value decreased; 3） the diffusion effect on the mechanical characteristics of soil was a slow process, c value gradually decreased, and φ value increased with time; and 4） with the increasing of concentration of heavy metal, c value gradually increased, and φ value decreased.