Study on the Influence of Performance Weakening of the Steel Supporting Movable End on the Stability of Enclosure Structures
In order to study the effect of weakened load-bearing performance of steel supports on the stability of en-closure structures,a numerical model was established based on the excavation project of a station on Beijing Metro Line 17.The influence of pre-applied axial force,yield load and initial compressive stiffness weakening of the mov-able end on the stability of enclosure structures was studied by numerical simulation methods.Combined with mea-sured data,the accuracy of the model was verified.The research results indicate that the loss of movable end pre-applied axial force is severe and mainly occurs at the moment of unloading the jack.The movable end has a signifi-cant weakening effect on the steel support,which is not conducive to controlling the stability of the foundation pit enclosure structure;The pre-applied axial force and initial compressive stiffness have a significant impact on the stability of the enclosure structure.When the yield load is not lower than that of the pile arrangement,it has no ef-fect on the stability of the enclosure structure.It is recommended to re-excavate after the completion of the steel support installation and for long intervals.The pre-applied axial force of all steel supports should be checked before excavation,and reapply the pre applied axial force to ensure the stability if necessary.
foundation pit engineeringenclosure structurestabilitysteel supportmovable endperformance weakening
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