Key Takeaways & Executive Findings
- •• Water-rich cracks amplify pressure peaks and gradients by up to 44.63% and 60.46% compared to tunnel walls, posing a risk of crack propagation. • The dominant frequency of pressure waves at the crack tip is 26.97% higher than in the tunnel, with PSD peaks increasing with depth. • Crack width has the most significant influence on pressure wave and gradient peaks, while transverse depth most strongly affects PSD peak values. • Water oscillation driven by inertia and pressure differences enhances pressure fluctuations at the crack tip, with higher water velocity leading to greater pressure gradients.
Abstract
Water-rich cracks represent common tunnel defects. Intense pressure waves generated by trains traveling through tunnels may undergo enhancement within water-rich cracks. Using the re-normalization group (RNG) k-ε turbulence model and volume of fluid (VOF) method, this study analyzes the spatiotemporal distribution, spectral features, and influencing factors of pressure wave propagation in water-rich cracks when two high-speed trains intersect in a tunnel. The flow mechanisms underlying the pressure enhancement within water-rich cracks are also revealed. The main conclusions are as follows: 1) The positive and negative peak pressure coefficients in water-rich cracks are 1.34 and −2.36, with corresponding pressure gradient peaks of 31.41 kPa/s and −34.01 kPa/s. Compared to the tunnel wall, the peak pressure coefficients and gradients exhibit increases of 34.41%/44.63% and 31.61%/60.46%, respectively. 2) The dominant frequency of the pressure wave power spectral density (PSD) at the crack tip is 26.97% higher than that in the tunnel. The PSD peak value continuously increases with depth and is the largest at the crack tip, representing an increase of 9.36% compared to the tunnel. 3) An increase in crack width reduces the peaks of pressure waves, pressure gradients, and PSD, while increases in vertical and transverse depths amplify these peaks. Crack width has the most significant impact on pressure waves and pressure gradients, while transverse depth has the most significant effect on PSD peak values. 4) Driven by inertia and pressure differences, the water body oscillates variably, enhancing pressure fluctuation amplitude at the crack tip. The higher the water body's movement velocity, the greater the pressure gradient at the crack tip. The above research results may provide a reference for crack harnessing in high-speed railway tunnels.
1. Introduction
Affected by multiple factors such as construction defects, environmental erosion, and the accumulation of operational time, lining cracking is a widespread issue in existing high-speed railway tunnels [1−3]. Under the influence of gravity and water pressure, groundwater gradually seeps from the rock mass towards the tunnel lining, with lining cracks serving as pathways for water leakage. As a result, water-rich cracks have become another common type of tunnel defect [4, 5]. When high-speed trains travel at high speeds within tunnels, the relatively enclosed nature of the tunnel space leads to the generation of intense aerodynamic pressure waves within the tunnel [6−8]. Under the action of these pressure waves, the cavities of cracks filled with water-air mixtures may experience enhanced pressure waves, which can gradually lead to crack propagation [9].
Numerous researchers have extensively studied the intricate aerodynamic phenomena resulting from high-speed trains traversing tunnels, covering aspects such as micro-pressure waves, aerodynamic pressures inside the tunnel and train, and train resistance. The research methods include theoretical analysis, field measurement, moving model experiments, and numerical simulations [10−12]. These aerodynamic effects have significant impacts on the train performance, causing fatigue damage to the train body [13]. ZHOU et al [14] researched the aerodynamic pressures generated during train passing through tunnels and during crossing events contributing to fatigue damage of base metals by 25%−28% and 61%−65%, respectively. TANG et al [15] analyzed the vibration of high-speed train outer windshields under aerodynamic loads. On the other hand, uneven pressure acting on the train surface induces train vibrations [16]. The intense pressure waves propagating from the train surface to the interior can
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YANG Wei-chao, HE Hong, LIU Yi-kang, ZHAO Lun, DENG E (2025). Effect of water oscillation inside lining cracks on interior pressure characteristics: Two high-speed trains intersect in a tunnel. Journal of Central South University. https://doi.org/10.1007/s11771-025-6139-4
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Frequently Asked Questions
What is the main focus of this study?
The study investigates how water oscillation inside lining cracks affects interior pressure characteristics when two high-speed trains intersect in a tunnel, using numerical simulations to analyze pressure wave propagation and enhancement in water-rich cracks.
What methods were used in this research?
The researchers employed the re-normalization group (RNG) k-ε turbulence model and the volume of fluid (VOF) method to simulate multiphase flow and pressure wave behavior in water-rich cracks.
What are the key findings regarding pressure amplification?
Water-rich cracks amplify peak pressure coefficients and gradients by up to 34.41% and 60.46% respectively compared to tunnel walls, and the dominant frequency at the crack tip is 26.97% higher than in the tunnel.
How do crack parameters influence pressure characteristics?
Increasing crack width reduces pressure peaks and PSD, while increasing vertical and transverse depths amplifies them. Crack width most significantly affects pressure waves and gradients, while transverse depth most strongly affects PSD peak values.
What is the practical significance of this research?
The findings provide a reference for crack harnessing in high-speed railway tunnels, helping to mitigate the risk of crack propagation due to aerodynamic pressure waves.
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