Laboratory Tests of Artificial Ground Freezing of Silty Sand using Pipe Piles

• Author / Creator

  Camacho Botello, Juan C

• In the Canadian Arctic, permafrost presents challenges to pile foundations for the existing and future infrastructure. The permafrost of Canada is vulnerable to the threats of climate change, which can lead to the long-term settlement of pile foundations in the Canadian Arctic, particularly during the summer when the permafrost is warm. Current solutions to this problem are more passive than active. One solution involves thermopiles that work in active mode during the winter but become dormant during the summer. Screw piles may be an alternative to foundation solutions for infrastructure in the Canadian Arctic. Prevention of screw pile settlement in warm permafrost is therefore critical to the performance of this pile type. To stabilize piles in warm permafrost, this research investigates an Artificial Ground Freezing (AGF) method that actively circulates glycol through screw piles. The experimental model evaluated a configuration that differs from the traditional AGF. Full-size close-ended pipe piles were installed into a soil chamber and filled with a glycol bath, and then glycol was circulated through a copper coil submerged in the glycol bath to freeze the soil around the pile. Effects of the pile installation method, water content, and initial soil temperature were evaluated. This configuration allows for reduction of the pump size, glycol reservoir and cooling energy in the system due to the small diameter of the copper coil. The initial water content and soil temperature were changed among a series of freezing tests. It is observed that soil temperatures of -13 ± 1 °C were reached within several hours. In addition, a closed-form solution (CFS) and a finite element analysis (FEA) were executed to compare the energy to be removed, the time needed for freezing and the refrigeration plant capacity versus laboratory results. The FEA
  iii
  predicts the temperature vs. time curves in the transient analysis. The CFS predicts the suitable energy extracted and its rate that is comparable to lab results.

• Subjects / Keywords

  • Laboratory Tests of Artificial Ground Freezing of Silty Sand using Pipe Piles

• Graduation date

  Spring 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-czpf-j522

• License

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