Abstract: This study investigates the spatial behavior of a deep excavation supported by a multi-level-single-level combined asymmetric system adjacent to a riverside environment. The No. 11 rectangular foundation pit of the Wuhan Xinhe Bridge project was used as the case study. A three-dimensional finite-element model based on the Hardening Soil model was developed and calibrated using field monitoring data. The excavation process was analyzed to clarify the spatial deformation characteristics of the retaining structure, ground-surface settlement, and basal heave. The results indicate that: (1) A distinct three-dimensional corner effect governs the deformation of the retaining structure, with the influence zone forming a triangular distribution along the sidewall. The corner effect becomes negligible when the horizontal distance from the pit corner exceeds 16.4 m and the depth exceeds 10.5 m.(2) Lateral deformations of the retaining structure show marked spatial heterogeneity. Deep displacements evolve from a cantilever to a bulging profile, peaking near the base. Under asymmetric constraints, top displacements in single-stage sections form a spindle shape, reversing from inward to outward, while multi-stage sections continuously deflect inward, forming a bow shape.(3) Ground-surface settlement outside the excavation is strongly asymmetric. Settlement on the multilevel support side is significantly larger than on the single-level support side. Settlement troughs perpendicular and parallel to the retaining wall exhibit spoon-shaped and arch-shaped profiles, respectively. (4) The vertical displacement inflection depth exhibits a three-stage trend with distance from the excavation corner: initial decrease, subsequent increase, and ultimate stabilization. This trend defines the spatial deformation boundary conditions for riverside deep excavations supported by asymmetric composite systems.

Key words: Asymmetric Supported, Spatial Effect, Corner Effect, Hardening Soil Model, Deformations