Development of temperature field of multi circle freezing wall in deep alluvium

The development of the temperature field of freezing wall is the most important part of the artificial freezing method in the shaft construction process, and has a great influence on the shaft excavation and safe construction.Due to the large-scale, long-term freezing in the underground, the soil undergoes complex changes, similarity simulation experiments cannot be performed, and numerical simulation software becomes the most direct assistant tool.In this paper, through a reasonable multi-hole layout method, the main factors, such as drilling deviation, the latent heat of water in the freezing process, the thermal conductivity, heat capacity at different temperatures and other factors, are considered.The development of temperature field with the coupling of multi-physics is established by using the numerical simulation software COMSOL Multiphysics with the measured data.The deep alluvium of a west air shaft in a mine was taken as the research object, and the simulation of the development of the 91 d temperature field of freezing wall was performed.The simulation lap time was 44 d, and the average development speed of the freezing wall was 25.36 mm/d.Compared with the measured lap time of 50 d and the average development speed of the freezing wall of 22.72 mm/d, there was a slight error.The simulation results are in good agreement with the actual situation.The study inferred the effect of the outer ring as the main freezing hole on the development speed of the freezing wall.Based on the previous simulation results, this simulation method has more theoretical significance and guiding significance in engineering.