Study Of Influence On Tunnel Aerodynamic Effects By Tunnel Portal Of Beijing-shanghai High-speed Railway

The tunnel portal is widely used on New high-speed rail way line, in the current time, the speed of EMU is higher than every time before, and how to use the tunnel portal to alleviate aerodynamic effects of tunnel better has become the key issues that must to be considered and address -ed in high-speed railway tunnel design community,and for the existing line tunnels to adjust to the promoting of the train Speed.In order to simulate the complex airflow inner tunnel truly, the Navier-Stokes equations with three dimensional, compressible and unsteady viscous fluid were taken as the control equations, and the technology named slippage grid was adopted. Then, the aerodynamic effects of the tunnel under different tunnel portals were studied systemicly combining with the model experiment, and some important conclusions were gained as following:The area and oblique slope of the slope protection around portal on the tunnnel entrence has little influence on the aerodynamic effects of the tunnel; The micro-pressure amplitude significantly increased until the area of slop protection on the the tunnel exit comes to 9 times of the tunnel area, then it does not change as the increase of the area, and the micro pressure wave amplitude decreases linearly with the decrease of slope protection oblique slope,when the slope of the tunnel exit slope protection changes from vertical to slope of 1:1.125, then micro pressure wave amplitude does not change with changes of the slope.Compared to the traditional wall tunnel portal on the tunnel entrance, the new kinds of tunnel portals almost has no influence on the maximum pressure amplitude of the train and tunnel surfaces, but they can ease pressure gradient of the initial compression wave and micro-pressure waves on the tunnel exit, and the mitigation effects of hat peak oblique tunnel portal are the best, in addtion, micro pressure wave amplitude decreases linearly with the decrease of oblique slope of the obliqued tunnel portal.The best length and enlarged transect ratio of enlarged transect windowless hoods were made clear; and compared to buffer structure, micro pressure wave changes were acquired when the portal is the combination of hat peak oblique and buffer structure; then the best vent ratio and opening form among windowed combination portal studyed in this paper...