Study On The Characteristics And Influence Law Of Micro-pressure Wave At Tunnel Portal Of 400 Km/h High Speed Railway

With the rapid development of high-speed railway in China,it is possible to design a high-speed railway tunnel with a speed of 400 km/h.However,the micro pressure wave effect at the tunnel portal is becoming more and more significant,which seriously affects the tunnel exit environment and building safety.At present,there is no targeted research at home and abroad on the variation characteristics and influence laws of micro pressure wave at the tunnel portal under the speed of 400 km / h.Taking the specification requirements as the optimization objective,a three-dimensional refined numerical model is established,the distribution law of micro pressure wave at the tunnel portal and its influencing factors are systematically studied at 400km/h,the mitigation effects of different buffer structures on micro pressure wave are analyzed,and the prevention and control measures for micro pressure wave at the tunnel portal of highspeed railway are put forward.The main research work is summarized as follows:(1)Based on the aerodynamic analysis theory of moderate subsonic flow,a three-dimensional numerical simulation model of buffer structure tunnel air train is established,and the field tests of transient pressure in the tunnel and micro pressure wave at the tunnel portal are completed,which verifies the reliability of the numerical simulation results.(2)Based on By fluent numerical simulation,the distribution characteristics and variation law of micro pressure wave at the tunnel portal are analyzed when the train passes through the tunnel at the speed of 400km/h;The influence of tunnel and train on micro pressure wave is discussed.(3)Based on the numerical simulation method of micro pressure wave at the tunnel entrance,the mitigation mechanism of micro pressure wave by buffer structure is revealed from different angles;The influence of different buffer structures on pressure gradient and micro pressure wave is analyzed;The length,area and slope of the buffer structure were optimized.(4)Based on the optimal length and area of the buffer structure,the reasonable combination of the buffer structure is demonstrated,and the relief mechanism of the pressure gradient by the pressure relief hole is studied;The influence of the parameters such as the area and distribution position of the pressure relief hole on the micro pressure wave is discussed,and the mitigation measures for the micro pressure wave at the tunnel portal at the speed of 400 km / h are obtained.