Thermo-Hydro-Mechanical Modeling of Artificial Ground Freezing: Application in Mining Engineering

For decades, artificial ground freezing (AGF) has been used as a temporary soil stabilization and waterproofing technique in multiple geotechnical engineering applications. Experience gained from AGF experiments indicates that the pore water expansion during freezing and the resulting pressure have the potential to induce ground movements in adjacent nonfrozen areas. This process was investigated in this paper using a comprehensive set of in situ temperature and displacement monitoring data collected in the Cigar Lake underground mine, Canada. The data set allowed to investigate the mechanical impact of freezing on a mine tunnel and prompted the need to derive a fully coupled thermo-hydro-mechanical model to predict ground temperature and displacements. Thermodynamically consistent, the model developed for this study is based on a macroscopic continuum approach and uses simplifying assumptions to overcome the computational difficulties associated with the modeling of complex mining environments over a long period of time. This model was used to perform three-dimensional finite-element simulations of the ground freezing and excavation activities in the Cigar Lake mine, showing good agreement with field measurements.