EXPERIMENTAL STUDY ON STRENGTH DAMAGE OF RED CLAY BY ZN²⁺ POLLUTION UNDER LEACHING

The exploitation of non-ferrous metal mines has caused serious heavy metal pollution to the surrounding soil. The effect of heavy metal Zn²⁺ on the strength and strength damage of Guilin red clay under leaching condition is studied using the self-made heavy metal leaching pollutant device. The indoor heavy metal Zn²⁺ contaminated soil is prepared with consolidation undrained triaxial shear test. The results show that the strength damage behavior of heavy metal Zn²⁺ to Guilin red clay is obvious. The shear strength is decreased by 30.61%~56.6%on average. The stress hardening relationship is strain hardening. The damage variable D is between 0.478~0.566. The damage of Zn²⁺ to Guilin red clay under leaching condition is mainly due to the irreversible erosion damage of the double clay layer and the double-layer structure of red clay. The strength of Zn²⁺ is decreased with the increase of Zn²⁺ concentration. The damage variable also increases, but the difference is small. This is because red clay has a certain adsorption effect on Zn²⁺ during prolonged leaching process, which leads to the similar effect of cumulative damage and high concentration of the soil, even under low concentration of contaminated solution leaching.