局部地层扩孔填充导热材料强化冻结试验

Experiment of the Intensified Artificial Freezing on Reaming Borehole Filled with Heat Conductive Material in Local Strata

针对立井冻结工程中复杂地层存在的导热性能差异大的问题,为达到对局部地层强化冻结并实现冷能优化的目的,提出了局部地层扩孔填充导热材料的冻结优化方案。为验证该方案的冻结优化效果,对富水砂土进行了单冻结管外覆导热材料的室内冻结试验及对比研究,得出不同低温盐水流量条件下,单管上下分段、有无外覆导热材料的冻结温度场分布规律及冻结壁特征。外覆导热材料冻结管可增加冻结壁厚度20.3%,降低平均温度4.5℃,增大低温盐水流量可明显增加强化冻结效果。

According to great heat transfer difference of strata in shaft construction projects with the artificial freezing method,a freezing optimization scheme,which boreholes filled with heat conduction material in local difficult-to-freeze strata,was proposed to intensify local freezing strata and realize optimization for cold energy utilization.In order to verify effect of the intensified freezing method,artificial freezing tests using a single freezing pipe covered with heat conduction materials were conducted to freeze water-rich sandy soils.The temperature field distribution and frozen wall?s characteristics of two different frozen wall sections were analyzed with two different flow rate of calcium chloride solution.The freezing pipe within heat conduction material could increase wall thickness by 20.3%,and reduce average temperature by 4.5℃ of frozen wall.The intensified freezing effect could be more obvious when calcium chloride solution flows rate increased.