Numerical simulation of heat transfer during in-situ thermal conduction remediation

Abstract

The current in-situ thermal conduction remediation technology has the problems of unclear heat transfer mechanism and unclear relationship between the main influencing factors. The verification of the coupled heat and moisture migration mechanism inside the soil is achieved by simulating indoor soil column experiments, and applied to the outdoor site size to clarify the effect of heat source temperature and initial moisture content on in-situ thermal conduction remediation under site size. An in-situ thermal conduction remediation coupling model was established, and a small-scale experiment was used to verify it by numerical simulation. The influence of the heat source temperature and initial moisture content on the in-situ thermal remediation was explored under the site size. The results showed that the in-situ thermal conduction remediation coupling model had high accuracy, and the average relative error between the simulation results and the experimental results was 1.30%. The duration of the boiling phase was inversely proportional to the temperature of the heat source, and the heating rate during the overheating phase was directly proportional to the temperature of the heat source. In engineering practice, the removal target should be the evaluation criterion instead of the cold spot temperature. The initial soil moisture content was within the range of 15%~35%. The lower the moisture content, the higher the thermal conductivity under the same temperature. The in-situ thermal conduction remediation technology was suitable for sites with low moisture content. If the initial moisture content was higher than 15%, proper drainage or water-stop curtains should be installed before restoration. The research results can provide a theoretical reference for the engineering practice application of in-situ heat conduction repair technology.