原位热传导修复过程中热量传递的数值模拟

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

目前原位热传导修复技术存在热量传递机理不明、主要影响因子作用关系不清的问题,通过模拟室内土柱实验实现对土壤内部热湿耦合迁移机理的验证,并应用到室外场地尺寸,明确场地尺寸下热源温度、初始含水率对原位热传导修复的影响作用。建立了原位热传导修复耦合模型,利用小试实验对其进行了数值模拟验证,在场地尺寸下探究了热源温度、初始含水率对原位热修复的影响。结果表明,原位热传导修复耦合模型准确度较高,模拟结果与实验结果平均相对误差为1.30%。沸腾阶段持续时间与热源温度成反比,过热阶段升温速率与热源温度成正比,在工程实践中应以去除目标为评价标准而不是冷点温度。土壤初始含水率在15%~35%范围内,相同温度影响下含水率越低导热系数越高,原位热传导修复技术适用于低含水率场地,初始含水率高于15%,在进行修复之前应进行适当排水或设置止水帷幕。该研究结果可为原位热传导修复技术工程实践应用提供理论参考。

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.