• 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.