Seismic stability analysis of tunnel face in inclined layered soils with unsaturated flow

• A novel analytical framework integrates modified pseudo-dynamic seismic loading and steady unsaturated seepage to evaluate tunnel face stability in inclined layered soils. • The derived suction stress distribution formula captures spatial variability under inclined stratification and hydraulic hysteresis, enhancing prediction accuracy. • The three-dimensional discretized failure model with integrated optimization yields critical face support pressures, validated against previous studies. • The study provides practical insights for shield tunneling design in seismic and unsaturated conditions, emphasizing the coupled effects of stratification and dynamic loading.