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.
MA Weibin
,
WEN Guochun
,
ZHU Huazhong
,
HAN Jiaqiang
,
WANG Chen
,
TIAN Jingwei
,
CHENG Aijun
. Sonic Boom and Alleviated
Measurements in Wan′an Tunnel
of Beijing-Hong Kong High-Speed Railway[J]. Tunnel Construction, 2024
, 44(7)
: 1431
-1439
.
DOI: 10.3973/j.issn.2096-4498.2024.07.010
