Freezing Temperature Field And Its Application In The Second Auxiliary Shaft Of Dingji Coal Mine

The physical and mechanical properties of frozen soil in the loose layer of Dingji Coal Mine are obviously different from those in other places.The continuous thickness of clay layer is larger,the freezing temperature is lower,and the quality requirements of frozen wall are higher.Therefore,in order to ensure the stability and safety of shaft lining during construction,it is necessary to carry out numerical simulation and field monitoring on the development of freezing temperature field.Based on the in-depth analysis of the research status of temperature field of multi circle freezing pipe at home and abroad,the calculation method of time-sharing numerical simulation of temperature field of multi circle freezing pipe is given.Taking the second auxiliary shaft of Dingji Coal Mine as the background,the time-sharing freezing temperature field and freezing wall thickness of auxiliary shaft are analyzed by means of theoretical analysis,numerical simulation and field measurement.The numerical model calculation of freezing temperature field before and after the intersection of freezing wall can be obtained by theoretical analysis..When the numerical simulation results can be scored,it is the best to start cooling when the difference freezing is delayed to the 60th day.According to the analysis of the intersection time and development of the freezing temperature field in the second auxiliary shaft,the thermal conductivity of the soil is closely related to the freezing effect,and the development of the freezing temperature field is relatively fast.The simulation results show that the average temperature of the shaft side with accumulated depth of 336m is-5.82? on the 200th day of freezing,so the excavation is stopped and the average temperature of shaft wall is-7.48? after 22 days,which meets the requirements of excavation.By comparing the measured temperature of temperature measurement hole with the numerical simulation results,the temperature change trend of C1-C6 temperature measuring hole at different time and different accumulated depth is basically consistent,which shows that the numerical simulation results are reliable and can provide decision support for site construction and freezing safetyFigure[117]table[4]reference[51]...