Thermal monitoring of frozen wall thawing after artificial ground freezing: Case study of Petrikov Potash Mine

This paper describes a case study of thermal monitoring of frozen wall thawing during shaft sinking at the Petrikov Potash Mine in the Republic of Belarus. This case study included gathering experimental data from which numerical simulation results were obtained. The unique feature of this research consists of developing an original optical fibre sensor and its application for distributed measurements of temperature in the shaft lining and surrounding rock mass. This new sensor automates measurements in real-time and provides significantly more data compared to traditional periodical measurement techniques using temperature probes or loggers. Sensor data are complemented by other distributed temperature sensing (DTS) data from vertical boreholes drilled near the shaft for thermal monitoring of the frozen wall state. Multiple series of measurements provided a clearer insight into the frozen wall thawing process. The data obtained from measurements were used for a numerical simulation and reconstruction of the temperature field in the surrounding rock mass. Real-time DTS monitoring combined with numerical simulation offers considerable possibilities for controlling and optimising mining operations. As described in this paper, the experience of using this new type of DTS sensor may be useful for specialists working with artificial ground freezing in mining and tunnelling.