Research on Polyurethane Applied to Energy Saving in Freezing Tube Insulation of Shallow Ground

According to the evaporation of the freezing value during the ground freezing construction in the shallow strata and the condition of the frost heaving dan ger to the safety of the mine permanent headframe, a single tube stable thermal conducted temperature distribution curve was applied to the temperature distribution of the freezing tube insulation layer and the surrounding soil and a sensible heat evaporation formula of soil was obtained.In combination with the phase converted heat fo rmula, the paper analyzed the phase converted heat values of the soil before and after the insulation of the freezing tube and provided the project site measured temper ature data and the numerical ftted curves.The adaptbility of the single tube stable temperature distribution curve was confirmed.The data analysis showed that after th e口159 mm freezing tube insolated with 50 mm polyurethane, the outer wall temperature reduction of the freezing tube would be 50% before the insulation and the temp erature within 3 m around the outer of the freezing tube insulated could be obviously reduced.As for the freezing tube with no insulation, the temperature within 1 m aro und the outer of the freezing tube would be reduced to 0 °C within 60 days and the temperature of 0 °C reached within 1 m around the outer of the freezing tube with the insulation would require over 210 days. With the insulation, within the same freezing period, the phase converted soil volume occurred would be less than the no insulati on condition and thus great latent heat freezing value could be saved.