Load transfer mechanism of deep braced excavation considering one-strut failure in marine and terrestrial deposit soft soil

Extensive coastal infrastructure construction has led to excavation failures causing social and economic losses. The heterogeneity, inter-layer interactions, and sensitivity of thick marine‑terrestrial soft soils complicate prediction and amplify 3D effects during one‑strut failure. However, the load transfer mechanism after such failure remains unclear due to limited research. Hence, this study investigates the mechanism of one-strut failure in deep braced excavation in marine and terrestrial deposit soft soil, based on a real project in coastal areas. The results indicate that one-strut failure has a significant impact on marine and terrestrial deposit soft soil, with both load transfer ratio and load increment ratio exceeding 20% and an influence radius up to 15 m. These effects intensify with higher axial forces and deep failure strut positions. Spatial load transfer induces adjacent-strut overload and potential progressive failure. Within the same horizontal level, the response patterns are similar, and under symmetrical strut arrangements, the load transfer displays pronounced symmetry. The bending moment and deformation of the diaphragm wall increase with larger strut forces and lower failure positions. However, for rigid walls, the influence zone is limited to within 10 m of the failed strut, and the overall stress‑strain response remains limited.