时速600公里磁浮列车隧道初始压缩波洞内传播特征和洞口微气压波特征

基于三维数值模拟方法，采用一维可压缩非定常不等熵流动模型和改进广义黎曼变量特征线方法，在隧道入口端未设置以及设置开口型缓冲结构条件下，分别研究了初始压缩波在隧道洞内的传播及洞口(默认为出口)的微气压波特性。研究结果表明:隧道入口设置开口型缓冲结构与无缓冲结构相比，其产生的初始压缩波的最大压力梯度下降了67.56%；初始压缩波在隧道内的传播过程中存在先激化后衰减的过程，其中未设置缓冲结构和设置开口型缓冲结构的临界长度分别为2和6 km，而满足微气压波控制标准的临界隧道长度分别为33和34 km；虽然开口型缓冲结构可较大幅度降低初始压缩波的最大压力梯度，但是对于长大隧道而言，由于传播过程中压缩波不断激化，开口型缓冲结构实际上对减缓微气压波的作用存在较大幅度的弱化，建议还应采取如竖井等工程措施以减缓激化；缓冲结构对不同隧道长度的洞口内压缩波的最大压力梯度的影响不同，所以需要结合不同类型缓冲结构和长度等因素来确定对应的最佳隧道长度匹配关系。 

Propagation characteristics of initial compression wave in cave and portal micro-pressure waves characteristics when 600 km·h-1 maglev train entering tunnels

Based on a three-dimensional numerical simulation method, a one-dimensional compressible unsteady non-isentropic flow model and an improved generalized Riemann variable characteristic line method were developed. The initial compression wave propagation in the tunnel and the micro-pressure wave characteristics at the portal (default exit) of the tunnel when the tunnel entrance without and with an opening buffer structure were investigated. Analysis results show that compared to the nonbuffer structure at the tunnel entrance, the maximum pressure gradient of the initial compression wave generated by setting the opening buffer structure decreases by 67.56%. During the propagation of the initial compression waves in the tunnel, intensification first occurs, followed by attenuation. The critical lengths of the nonbuffer and opening buffer structures are 2 and 6 km, respectively, whereas the critical lengths of the tunnel satisfying the control standard of the micro-pressure waves are 33 and 34 km, respectively. Although the opening buffer structure can significantly reduce the maximum pressure gradient of the initial compression waves for a long tunnel, owing to the continuous intensification of the compression wave during propagation, the effect of the opening buffer structure on the mitigation of the micro-pressure waves is significantly weakened. Engineering measures (such as shafts) should be adopted to mitigate intensification. In addition, the effects of the buffer structure on the maximum pressure gradient of compression waves are different in the portals of different tunnel lengths. Therefore, the different types of buffer structure and length factors should be combined to determine the corresponding optimal tunnel length matching relationship. 1 tab, 24 figs, 33 refs.