Parameter Optimization and Numerical Calculation of Forced Ventilation System for Expressway Tunnel Construction
In order to clarify the influence of the parameters of the pressure ventilation system on the ventilation effect during tunnel construction,the fluid mechanics software Fluent is used to establish a calculation model for pressure ventilation,the flow field characteristics are affected by four factors:the angle of duct arrangement,the distance of duct exit,the height of upper step and the length of step.The results show that the ventilation efficiency is the highest when the air duct angle is 30° in full-section construction,and the ventilation efficiency is the highest when the air duct angle is 50° in step construction.When the height of the upper step is about 4 m,the space vortex between the step and the jet is the smallest,and when the length of the step is about 10 m,the ventilation efficiency is the highest.Therefore,the angle between the center of the air duct and the middle line of the tunnel should be about 30° when the full-section construction and the pressing ventilation method are adopted,and when the step construction and the pressing ventilation method are adopted,the angle between the center of the air duct and the middle line of the tunnel should be about 50°.The height of the upper step should be about 4 m,at which time the eddy current below the air duct and in front of the step is the smallest.The ventilation efficiency is the highest when the length of the step is about 10 m,the jet can be fully developed.
NETL
NSTL
万方数据
