Study on Cooling Effect of High Ground Temperature Tunnel Under Forced Ventilation
In order to analyze the cooling effect of high ground temperature tunnel under forced ventilation,a 3D simulation model was established based on typical double track railway tunnel.The influence of wind speed,wind temperature,rock temperature,distance between air outlet and heading face,and ventilation pipe layout on the cooling effect was studyed,and the results were compared with theoretical calculations.The results show that there is vortex near the heading face,which is conducive to local temperature reduction.As the wind moves away from the heading face,it gradually transitions towards laminar flow,and the average tunnel temperature also increases.The higher the wind speed is,the lower the tunnel temperature becomes with more uniform temperature field,and the faster it can reach a stable temperature state.The lower the wind temperature is,the lower the tunnel temperature becomes,and the cooling effect is more significant than increasing the wind speed.The higher the rock temperature is,the higher the tunnel temperature becomes,and the influence depth of ventilation on the temperature field of surrounding rock is very limited.The larger the distance between outlet and heading face is,the higher the tunnel temperature becomes after ventilation.Therefore,the air outlet should be followed up in a timely manner to minimize the tunnel temperature.However,the ventilation pipe layout has little impact on the cooling effect.The uniformity of temperature distribution along the longitudinal direction is worse in theoretical analysis compared to numerical simulation.Overall,forced ventilation can effectively reduce the temperature inside the tunnel.When the wind speed is 20m/s and the wind temperature is 14℃,the cooling rate can reach 66％.
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