回填材料对土壤原位热传导修复的影响及数值模拟

Effects of backfill materials on in-situ thermal conduction heating remediation of soil and numerical simulation

原位热传导修复技术是一种有机污染土壤高效修复手段。由于施工过程中加热井与土壤间会存在一定空隙,关于是否使用回填材料以及回填材料的选取原则,尚未有明确的指导意见。利用实验和数值模拟方法,对原位热传导修复过程中回填材料的影响进行了研究,分析了不同加热温度(200、400、600、800℃)、回填材料(空气、原土)、回填厚度(40、100、150 mm)对传热的影响。结果表明,基于实验数据所建立的原位热传导数值预测模型是可靠的,模拟计算值与实测值最小平均相对误差为6.69%;当加热温度高于450℃时,无回填料时传热效果更好;当加热温度小于300℃时,用土壤回填较好;在300~450℃时,有无回填料传热效果相差不明显;原位热传导修复技术工程在应用过程中,回填材料厚度100 mm时传热效果最佳。本研究结果可为污染土壤原位热传导修复的工程实践提供参考。

In-situ thermal conduction remediation technology is an efficient remediation method for organic contaminated soil.As there will be a certain gap between the heating well and the soil during the construction process,there is no clear guidance on whether to use backfill materials and the selection principle of backfill materials.Using experimental and numerical simulation methods,the influence of backfill materials in the insitu thermal conduction heating remediation process was studied,and different heating temperatures(200,400,600,800℃),backfill materials(air,original soil),and backfill thickness(40,100,150 mm)on heat transfer.The results showed that the in-situ thermal conduction heating numerical prediction model based on experimental data was reliable,and the minimum average relative error between the simulated calculated value and the measured value was 6.69%;when the heating temperature was higher than 450℃,the heat transfer effect was better without backfill;when the heating temperature was less than 300℃,it was better to backfill with soil;at 300~450℃,the heat transfer effect with or without filler was not obvious;in the application process of the in-situ thermal conduction heating remediation technology engineering,the heat transfer effect was best when the thickness of the backfill material was 100 mm.The results of this study can provide a reference for the engineering practice of in-situ thermal conduction heating remediation of contaminated soil.