高速铁路长隧道压缩波波前变形规律分析

高速列车进入隧道时产生的压缩波在长隧道中传播时会产生波前变形，即波前压力梯度发生变化。线路测量和学者的研究表明，隧道出口处微气压波的强度与压缩波波前压力梯度最大值成正比，而微气压波的大小又与隧道出口的爆破音直接相关，因此有必要研究压缩波在长隧道中传播时的波前变形规律。采用计算流体力学三维动态仿真计算方法，对长隧道内压缩波的生成和传播过程进行研究。证明了压缩波的波前变形不仅与初始压缩波生成时的惯性运动和气体摩擦相关，而且与列车在隧道中的运动相关，即列车运动产生的能量输入会影响压缩波波前的变形。通过多工况计算，获得了隧道内压力梯度的最大值及其出现位置与列车速度和隧道阻塞比之间的变化规律。

Deformation law of compression wavefront in long tunnel of high-speed railway

A compression wave will be generated when a high-speed train suddenly enters into a tunnel.The wavefront of the compression wave deforms as it is propagating in a long railway tunnel,which means the pressure gradient of the wavefront varies along the tunnel.The intensity of micro-pressure wave at the tunnel exit is proportional to the maximum pressure gradient of the compression wave,and the sonic boom at the tunnel exit is directly related to the intensity of the micro-pressure wave.So it is necessary to study the law of the compression wave deformation in long tunnel.In this paper,the generation and propagation process of the compression wave in a long tunnel are investigated by using three dimensional CFD method.It is proved that the deformation of the wavefront is not only related to friction between the air and the wall of the tunnel and the inertial motion of the compression wave,but also related to the motion of the train that is to say the train movement in the tunnel will input energy to the back of the compression wave and hence affect the deformation of the compression wavefront.Through the calculation of multiple operating conditions,the variation trend of the maximum pressure gradient and its appearance position relating to train speeds and to tunnel blockage ratios in a long railway tunnel are obtained.