水热耦合对冻土区埋地管道土壤温度场的影响

冻土区埋地热油管道最常见的安全问题是冻害破坏。当环境温度降至冰点以下,土壤中水分的冻结将伴随着水分向冻结前锋迁移,产生不均匀冻胀,加之周期性不可逆的冻融循环,极易造成管道失稳甚至破裂。研究管道冻害成因,应先预测埋地管道周围土壤冻融过程中温度场的变化,以及温度场与水分场的变化关系。采用有限体积法,建立土壤多孔介质水热耦合相变模型,利用SIMPLER算法进行数值求解,为了研究水分对土壤温度场的影响,这里对无水土壤和饱和含水土壤两种极限情况进行对比分析,结果表明：在输油管道运行初期,两种情况土壤温度场接近,随着运行时间的延长,饱和含水土壤温度场偏高,水分迁移和冰水相变对土壤温度场具有一定影响。

Influence of Hydrothermal Coupling on Hot Soil Temperature Field Around Underground Pipelines

A freezing damage is a common problem for pipelines buried in frozen underground area.When the temperature drops below freezing,frozen soil moisture moves forward along with freezing of water,which can result in heterogeneous freezing expansion,combined with periodic freeze-thaw cycle,pipelines are easy instability or break.To study freezing damage and take scientific and effective measures to prevent freezing damage,it is necessary to predict the changes of the temperature field of frozen soils around underground pipelines in the freeze-thaw process,and the change relationship between the temperature field and moisture field.In this paper,a porous medium soil hydrothermal coupling phase change model was established with finite volume method,the temperature field of the soils around underground pipelines was numerically simulated by using SIMPLER method,influence of moisture on soil in the temperature field was studied,the comparative analysis of anhydrous soil and water saturated soil was carried out.The results show that during initial operating stage,two cases of soil temperature field are close,with running time going on,the temperature field of water saturated soil is high,the moisture transfer and phase change have definite effect on heat transfer of the soils.