Abstract:

Artificial ground freezing (AGF) has proven to be an effective geotechnical method for stabilizing the ground structure and controlling the groundwater flow in underground mines. Selective artificial ground freezing (S-AGF) is particularly designed such that the ground freezing applies only in the areas that are needed to be frozen (a.k.a., active zone) and reduces the refrigerating energy via air gaps elsewhere (a.k.a., passive zone). In this way, the S-AGF makes great use of the practicability of AGF yet circumventing the drawbacks of high energy consumptions in AGF, which in turn mitigates the carbon emission from refrigerating plants to a great extent. The S-AGF has also been used as a cost-effective and environmentally friendly technique in underground mines, because the active zone is usually far away from the ground surface, making a large passive zone for heat insulation by air gaps. In this study, we develop a space-marching analytical model to rapidly predict the transient temperature in both radial and axial directions. Specifically, the radial temperature is obtained by the asymptotic solution to a two-phase Stefan problem, while the axial temperature is calculated through a space-marching algorithm to march the radial temperature in a layer-by-layer fashion. The modeling results are also validated against a set of field data from the Cigar Lake uranium mine in Saskatchewan, Canada. It can be concluded that the presented mathematical model is capable of simulating two-dimensional temperature profile over time in an accurate and computationally efficient way.

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Ahmad Zueter