<p>This study presented a three-dimensional numerical investigation of cross-passage tunnel behavior constructed between twin tunnels in soft ground conditions. The analysis employed advanced constitutive modeling to evaluate the influence of soil model selection on predicted ground deformation and structural response. Three widely used models Mohr–Coulomb, Hardening Soil, and Hardening Soil with Small-Strain Stiffness were implemented to simulate staged tunnel excavation and lining installation. The results revealed that excavation of the cross passage induced significant localized settlement and stress redistribution, particularly at the junctions with the main tunnels. The Hardening Soil model predicted the largest settlements and lining forces, while the Mohr–Coulomb model significantly underestimated deformations. The Hardening Soil with Small-Strain Stiffness model yielded intermediate results, offering a balanced prediction of settlement and internal forces by capturing small-strain stiffness degradation. Peak settlement values reached maximum in the cross-passage zone, with notable hoop force concentration near tunnel intersections. Validation against experimental data demonstrated good agreement, confirming the reliability of the numerical approach. The findings highlighted that accurate prediction of ground-tunnel interaction in soft soils strongly depended on the chosen constitutive model. This study provided practical insights for optimizing support design and minimizing deformation risks in cross-passage tunnel projects.</p>