Artificial ground freezing: A review of thermal and hydraulic aspects

The artificial ground freezing (AGF) is one of the most popular ground-support methods. Driven by its reliability, compatibility with a wide range of ground types, and low impact on the environment, the AGF became one of the most favorable geotechnical-support methods in various mining, civil, and environmental projects. Over the last few decades, there has been a growing interest in the AGF. Several studies have been conducted to investigate the complex phenomena associated with the AGF process. This paper provides a comprehensive overview of related publications that discuss the thermal and hydraulic characteristics of the AGF. It reviews the most common types of AGF systems, their basic configurations, and their main applications. It also examines a series of analytical, numerical, and experimental analyses undertaken to assess and quantify the heat transfer and fluid flow during the AGF process. Throughout the literature review, one can observe the significant improvement of the problem formulation during the last decades. Previously, the multi-phase heat transfer was formulated by solving the conduction energy equation. This approach, however, has been advanced to another level of complexity by considering the convective groundwater flow. Currently, there are two common approaches to model the heat transfer of AGF problem: (i) the apparent heat capacity formulation, (ii) and the enthalpy-porosity formulation. It is concluded that the subject of AGF has received a lot of attention in the last decade, especially in environmental and civil applications. However, the number of experimental or analytical studies is very limited. Thus, there is a vast opportunity for research and development of the AGF.