Stability of lead-zinc contaminated soil cured by soybean urease without CaCl₂

In order to examine the effect of soybean urease without CaCl₂ curing treatment on the long-term stability of lead-zinc contaminated soil after restoration without greatly improving the strength of cultivated soil, the long-term stability of contaminated soil after restoration under the complex environment of dry-wet cycles, freeze-thaw cycles and acid rain leaching was discussed by using pH value, heavy metal ion leaching rate and soil heavy metal occurrence form, respectively. The results show that the surface strength of the soil cured by soybean urease without CaCl₂ is significantly reduced and the permeability is improved compared with that cured by EICP. With the increase of dry-wet cycles and freeze-thaw cycles, soil pH value decreases slowly but remains weakly alkaline, and the increasing trend of heavy metal leaching rate slows down. Under the action of acid rain, with the increase of pH value of acid rain solution, the contents of Pb²⁺ and Zn²⁺ in leached solution gradually decrease, and both meet the requirements of hazardous waste disposal regulations. In addition, different types of acid rain have different effects on repaired soil, and its stability under sulfuric acid rain is better than that under nitric acid rain.