Progressive failure mechanisms and dynamic load redistribution in asymmetric excavation with partial bracing collapse

Current research on the progressive failure mechanisms and dynamic load transfer paths induced by localized failure in asymmetrical excavation support systems re-mains insufficient. This study, based on the "component removal method," designs a model test for local failure of internal supports in an asymmetrically excavated foundation pit. Through refined three-dimensional numerical modeling, multi-condition comparative validation is conducted, revealing the coordinated evolution mechanism of deformation and internal force response following local support failure. Key findings demonstrate: post-failure reduction in lateral stiffness of supporting slabs induces inward dis-placements, amplifying surrounding soil settlement, with significantly greater dis-placement increments observed in deeper excavation zones compared to shallower regions; Axial force redistribution follows a proximity amplification and distal attenuation pattern, with adjacent struts experiencing force increases to 1.48 times after single strut failure, while distant struts show reductions to 0.93 times; Bending moments increase in remote support structures due to soil arching effects, reaching up to 427 N·m on the shallow side, whereas near-field structures exhibit moment reductions attributed to pronounced unloading effects from significant slab displacement; The secondary retaining wall exhibits cantilever-like behavior, with bending moments rising to 450 N·m post-failure.