Study on the Influence of the Performance Weakening of the Disconnectable Coupling (DC) Joint of Steel Support on the Retaining Structure of a Foundation Pit

In order to quantitatively study the influence of the weakening of the disconnectable coupling joint (DC joint) on the retaining structure, the pre-axial force retention performance of the steel support, the axial force of the steel support, the horizontal displacement of the diaphragm wall, and the ground settlement around the foundation pit were monitored during the construction of the foundation pit. The evolution process of the monitoring data was analyzed, and the corresponding numerical model verified by the monitoring data was established. The influence of the yield load of the DC joint, the initial compression stiffness, and the weakening of the pre-axial force on the stability of the retaining structure was studied by numerical simulation. The results show that the pre-axial force of steel support is only 67% of the design value when the soil below is not excavated within 24 h. The DC joint has a significant weakening effect on the steel support, which is unfavorable for the stability control of the foundation pit retaining structure. The pre-axial force and initial bending stiffness have a great influence on the stability of the retaining structure. When the yield load is not lower than that of the row piles, the DC joint has no effect on the stability of the retaining structure. This model can predict and analyze the deformation trend under different working conditions to a certain extent, providing certain reference value for safety plans during construction.

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