The determination of the support pressure is critical for the excavation face stability of deeply buried shield tunnels in soft-over-hard ground conditions. Based on the limit equilibrium method, this study establishes a calculation model for the limit support pressure, which considers the variation in slip surface inclinations and comprises a friction arch zone, a load-bearing arch zone, and a multi-layer wedge slip zone. Validated against a case study and numerical simulations, the model is proven to effectively predict the limit support pressure. The results indicate that a reduction in support pressure exacerbates soil displacement, with more significant deformation in the upper soft soil. Moreover, the limit support stress ratio exhibits a non-linear decrease as the buried depth ratio increases. An increase in the cohesion and internal friction angle of the upper soft soil leads to a linear decrease in the limit support stress ratio, whereas an increase in the proportion of the soft soil layer results in its near-linear increase. This research provides a valuable reference for predicting the limit support pressure for tunnel excavation faces in similar geological conditions.