Study on Vertical Deformation of Steel Pipe Column and Influence on Main Structure of Cover Excavation Pit in Multi-layer Confined Water Stratum
The steel pipe column is the main vertical bearing member of underground structure constructed by cover excavation method.Under the combined action of excavation unloading and underground water at the bottom of foundation pit,the steel pipe column will produce vertical deformation,produce additional stress in underground structure and affect the structure safety.Therefore,based on the deep foundation pit of the transportation hub of Beijing Municipal Administrative center,firstly,the excavation scheme of the foundation pit which is conducive to controlling the vertical deformation of the steel pipe column is proposed.Then,the effects of foundation pit excava-tion and different dewatering schemes on the vertical deformation were analyzed by numerical simulation method to determine the suitable dewatering scheme;The vertical deformation was monitored during the construction process.Then,the measured vertical deformation was equivalent to the forced displacement.The additional internal force generated by the vertical deformation was calculated.The additional internal force and the original internal force were superimposed.The influence of the vertical deformation on the safety of the underground structure was analyzed under the most unfavorable conditions.