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.