Huajun Liu, Qiang Jia
• Proposes an innovative continuous arched composite-section caisson structure for underground garages. • Identifies an optimal rise-to-span ratio that minimizes bending moments through systematic analysis. • Demonstrates superior mechanical performance via comprehensive 3D numerical simulations. • Achieves significant reduction in deformation and stress concentrations compared to conventional designs. • Combines structural efficiency with enhanced spatial utilization for urban applications. • Validates the design's advantages through theoretical and numerical investigations. • Offers practical solutions for underground construction in space-constrained urban environments. This study proposes a continuous arched composite-section caisson-type underground garage structure and investigates its load-bearing characteristics through ANSYS numerical simulations. The results indicate that when the rise-to-span ratio of the intermediate section's outer arched wall is 0.1434, the bending moment approaches zero, representing the optimal mechanical state. Three-dimensional analysis demonstrates that under this optimal ratio, structural deformation is minimized, while concrete and steel stresses are predominantly compressive, significantly reducing material usage. The design combines the mechanical advantages of arched structures with the spatial efficiency of rectangular layouts, making it suitable for urban confined spaces with economic and construction benefits. The study provides a theoretical basis for optimizing caisson-type underground garages, though further research is needed to address complex loading conditions and long-term performance.