Abstract Based on the basic principle and method of fluid mechanics,heat transfer and dynamics of air,a cold temperature field model is deduced. The impact of surrounding rock tunnel ventilation is considered in this model. This model includes:temperature control equations of surrounding rock,air temperature field control equations in tunnel and wind flow control equations of turbulence field. On this basis,numerical analysis method is used to discuss the temperature field change law of surrounding rock and thermal insulation measures of Galongla tunnel in Tibet under the condition of ventilation. The study results show that:before tunnel excavation,there is a clear temperature fluctuation in the shallow mountain changing with the change of season;and the apparent change appears at the depth of 18 m. When rock depth is more than 18 m,the temperature fluctuation amplitude of rock mass with the change of season is less than 0.5 ℃. Due to ventilation effect,the temperature of surrounding rock presents the adverse conditions of below 0 ℃ within the scope of inlet and outlet sections of tunnel at the most coldest month(January) after the breakthrough of tunnel. Further research shows thats:at the inlet section of 600 m and outlet section of 400 m in Galongla tunnel,heat preservation material such as phenolics with the thickness of 6 cm is laid on secondary lining surface,which can effectively prevent the Galongla tunnel lining and rock from freeze-thaw damage.
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