列车运营速度不断提高容易引发高速铁路长大隧道音爆现象，对洞口声环境及行车秩序造成负面影响，而音爆发生机制及相关空气动力学指标特性尚不明确。基于京港高铁万安隧道实车试验,从音爆产生机制和原因、音爆声波频域特性、压力梯度与微气压波规律展开分析，并结合三维精细化数值仿真增补实车测试工况，针对测试隧道探究不同缓解措施的气动缓解效果。结果表明： 1)压缩波在无砟轨道隧道内传播过程中，在非线性效应作用下发生激化，由此诱发了音爆的发生。2)音爆发生时，隧道洞外和洞内的音爆噪声中0~20 Hz的低频段占主要部分。3)列车时速低于300 km时，压缩波在隧道内激化较弱，隧道洞口未出现音爆噪声；当列车时速达到300 km时，压缩波在隧道内激化显著，洞口微气压波幅值较时速250 km时增长近5.5倍，洞口能够监测到明显的音爆噪声。4）对于测试隧道，3种缓冲结构型式缓解措施对于微气压波的缓解效果排序为进、出口同时增设动力学开孔＜出口增设动力学开孔＜开启3处斜井。
The continuous improvement
of train operation speed is likely to lead to sonic booms in long tunnels of
high-speed railways, negatively impacting
the acoustic environment and traffic order at tunnel entrances. However, the
mechanism of sonic booms and related aerodynamic index characteristics remain
unclear. Based on a real vehicle test conducted in the Wan′an tunnel of the Beijing-Hong Kong high-speed railway, the authors analyze the mechanism and causes of sonic
booms, the frequency domain characteristics of the phenomenon, the pressure
gradient, and the behavior of micro-pressure waves. A
three-dimensional refined numerical simulation
supplements the real vehicle test conditions, examining the aerodynamic
mitigation effects of various measures for the test tunnel. The results reveal
the following: (1) The compression wave intensifies under the nonlinear effect
during its propagation in the ballastless track tunnel, leading to the
occurrence of sonic booms. (2) When sonic booms occur, the low-frequency band of 0－20 Hz is the main
component of the sonic boom noise both outside and inside the tunnel. (3) When
the train speed is below 300 km/h, the compression wave intensifies weakly
within the tunnel, and no sonic boom noise is detected at the tunnel entrance.
However, at a train speed of 300 km/h, the compression wave intensifies
significantly in the tunnel, and the amplitude of the micro-pressure wave at the entrance increases nearly 5.5 times compared to
that at 250 km/h, resulting in detectable sonic boom noise at the entrance. (4)
For the test tunnel, the mitigation effects of three types of buffer structures
on micro-pressure waves are ranked as follows: adding
dynamic openings at both the inlet and outlet simultaneously < adding
dynamic openings at the outlet < opening three inclined shafts.
