Abstract: To explore the feasibility of resistivity method in monitoring the drying shrinkage of heavy metal contaminated purple soil, zinc, which is the most common and most abundant contaminant, was selected based on two-electrode method. In this study, the influence of zinc content on evaporation, shrinkage and resistivity during drying shrinkage was analyzed, and a resistivity model was deduced. The results showed that according to the evaporation amount, the drying shrinkage process can be divided into three stages: constant rate, variable rate, and residual. In the stage of variable rate stage, the evaporation rate firstly increases and then decreases, and its peak value increases with the increase of zinc content. The higher the zinc content is, the slower the shrinkage increases in the early stage; the earlier it stabilizes in the later stage, the smaller the final shrinkage is. The resistivity increase slowly at first and then rapidly. The higher the zinc content, the slower the resistivity increases in the early stage, but the faster it increases in the later stage. The resistivity model is expressed by evaporation and shrinkage, and it is related to zinc content within a certain range. The zinc content affects the evaporation rate at different stages, inhibiting the shrinkage deformation, and has an increasingly stronger effect on the resistivity. The model illustrates the relationship between them, which provides a basis for measuring the drying shrinkage deformation of purple soil through the resistivity method.

Key words: purple soil, drying shrinkage, zinc pollution, resistivity, shrinkage, evaporation