粉质粘土冻融过程中水热迁移特性的实验研究

Experiment Study on the Characteristics of Heat and Water Migration Process in Silt Clay during Freezing and Thawing Process

当利用土壤源热泵供暖时,地埋管周围的土壤有时会形成冻土。为了研究土壤冻融过程中的水热迁移特性,使用足尺冻融实验台,对哈尔滨地区粉质粘土进行了冻融实验。实验结果显示土壤在冻结过程中水分迁移量与冻结速率成反比关系,已冻结区域的含水率基本不发生变化;沿冻结方向分为水分聚集区、输运区和水源区,聚集区在冻融实验前后含水率变化最大,输运区在冻融实验前后含水率变化最小;土壤在冻融状态转换的过程中,会出现含水率突变的现象,变化强度与冻融速率成正比关系。

When utilizing ground source heat pump,occasionally the surrounding soil around underground heat exchanger can be turned into frozen soil.In order to study the characteristics of heat and water migration process during freezing and thawing process in soil,experiments were conducted on Harbin silty clay by using a full-scale test bench.The experimental results showed that the amount of migrated water was inversely proportional to the freezing rate;the water content kept constant in the frozen zone.The specimen can be divided into three parts along the freezing direction,which are enrichment region,transportation region and source region.The difference in the water content in the enrichment region was the highest and the lowest in transportation region.Abrupt changes on water content were observed in the transition process in frozen soil,and the intensity was proportional to the freezing rate.