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

According to great heat transfer difference of strata in shaft construction projects with the atificial freezing method, a freezing optimization scheme, whic h boreholes flled 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 co nducted 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 temperat ure by4. 5。C of frozen wall. The intensified freezing effect could be more obvious when calcium chloride solution flows rate increased.