• A novel analytical method based on hydraulic fracturing theories is proposed to characterize seepage at tunnel-gasketed joints.
• Analytical expressions for interface opening and liquid pressure are derived, enabling quantitative prediction of gasketed interface behavior.
• Parametric analysis reveals that the liquid tip coordinate is influenced by negative pressure in the liquid lag region, which is related to initial contact stress.
• Comparative analysis under two limit states confirms excellent agreement with previous research, supporting the method's reliability for waterproofing design.