Numerical simulation and measurement analysis of the temperature field of artificial freezing shaft sinking in Cretaceous strata

Targeting the challenging analysis of the temperature field of the artificial freezing shaft sinking projects in Cretaceous strata, this study used the Hongqinghe air shaft freezing project as an example to perform a numerical simulation and measurement analysis of the temperature field of shaft sinking via the artificial freezing method in Cretaceous strata. First, the thermal physical parameters and mechanical properties of frozen Cretaceous rock were measured in the lab. Based on the engineering geological conditions and test parameters, the Hongqinghe air shaft freezing parameters were designed, and the preliminary scheme of the freezing project was obtained, in which a single ring of freezing holes was arranged in Cretaceous strata, the freezing wall had a design thickness of 3.7 m, and the average temperature was -12°C. Next, a numerical model for the temperature field of the freezing project was established to predict and analyze the effective thickness, average temperature, and shaft wall temperature of the frozen wall at different depths of shaft excavation. Finally, a comparison and analysis of field temperatures measured at the inspection holes and shaft walls showed that the numerical simulation results generally agreed with the field measurements. The field measurements showed that at the initial stage of freezing, the cooling rates of fine-, medium- and coarse-grained sandstones were 0.364 °C/d, 0.397 °C/d and 0.440 °C/d, respectively. Informatized construction enabled the air shaft freezing project in the Hongqinghe coal mine to be completed successfully.