Szkoła Eksploatacji Podziemnej

The freeze shaft method has been used in the mining industry since the late 1800s. During the period of shaft construction, this method provides temporary ground support and water control through artificial ground freezing.
There has been significant progress in the field of fibre-optic temperature sensing, directional drilling techniques, three-dimensional freeze-pipe survey methods and the development of numerical calculation methods over recent years. Despite this, many ground freeze designs are still conducted through the application of analytic, semi-empirical design methods. Thus, opportunities for design optimisation are often missed.
The development of the Ust-Jaiwa potash mine, located in the Perm Region of the Russian Federation, commenced in early 2012. It involves the construction of two vertical shafts with a final diameter of 8.0 m and a depth of approximately 500 m each. Both shafts are constructed through the application of the freeze shaft method with a freeze depth of 250 m. A freeze plant with a freeze capacity of 3.0 MW was installed to cope with local ground freeze challenges, including the freezing of salt-marl strata at a melting temperature of −21°C.
In this paper, conventional and advanced methods of freeze circle design are discussed in the context of their application for the Ust-Jaiwa freeze shaft project. The results of predictive calculations for the determination of frost development are outlined, and respective conclusions are drawn.
Moreover, the advantages of implementing numerical calculation methods for the back-analysis of thermal rock material parameters are demonstrated. The results of back-analysis are subsequently used for the predictive computations of frost development. It is concluded that state-of-the-art techniques for on-site monitoring and numerical analysis provide a significant potential for both the design and operation of large-scale freeze plants.