Deformation and Force Analysis on Retaining Structure of an Open-excavated Subway Station by Monitoring and Numerical Simulation

The simulation of forced deformation on retaining structure of an open-excavated subway station was carried out using the software FLAC^3D,and a comparative analysis with field data was accomplished.The established numerical simulation methods are used to analyze the horizontal deformation of pile body in different pre-axial force loading schemes.The relationship between brace stiffness variation and retaining structure deformation and the relationship between variation of fender pile stiffness and retaining structure deformation were studied.Resultsshow that 1) steel support pre-applied a reasonable axial force can prevent and reduce the deformation of retaining structure,and a recommended value is 80% of the design value of the axial force;2) pit top horizontal displacement can be reduced by increasing the rigidity of the steel support in strict deformation requisition;and 3) the pile horizontal deformation will decrease obviously with the increase of fender pile diameter,and the effect will become inconspicuous when the pile diameter is to large.From the perspective of controlling pit deformation,structure designs should select an appropriate size of the pile diameter and take economic benefit into account.