The Study Of Deformation Laws Of Deep Foundation Pit And Its Design At A Metro Station In Xi’an

The chesis is based on the Construction of deep foundation pit engineering of a station ofXi’an Metro Line3, the deep foundation pit supporting structure stress and deformation arestudied and analyzed systematically, with the methods of theory analysis, monitoring andnumerical simulalion.Firstly, the commonly used foundation pit precipitation method and sheet pile wallstructure commonly used design theory, characteristics and design method are analyzed.Through the design of foundation pit precipitation, the reasonable precipitation scheme for theproject is given. By deep foundation pit retaining scheme comparison and selection, It get thestation of the first phase of design scheme of the deep foundation pit retaining structure,andthen calculate and check calculations of flexural torque and shear force of structural supportand guard post.Secondly, considering main factors causing deformation of retaining structures, theengineering geological conditions, hydro-geologic condition, and construction conditionsusing FLAC3D software for caleulating simulalion,the numerical simulation of the law offorce and deformation of retaining structure are carried out,During the process of foundationpit excavation, the simulation results show that the stress and deformation of foundation pit islimited to an acceptable range,and the design scheme is reasonable; The result also indicatesthat deep foundation pit has “spatial effect”, the horizontal displacement of the corner pile issmaller than the middle pile of Foundation pit; The steel have limiled action to thedeformation of shotcrete deep-fourdation pit; The size of load around the foundation pit andfoundation form that directly affect the distribution of the horizontal displacement of the pileand the maximum value of pile of horizontal displacement have a great influence on the deformation of retaining structure.Finally, The design of monitor scheme and inspeetion work are completed, it wasanalyzed that the deformation law of pile body and support axial force variations, and it isclose between the numerical results and theoretical calculation. The resulte indicates that thedeformation and stress of retaining structure of deep foundation pit of subway station meet thedesign requirements, the deep foundation pit is in a stable state in the excavation process.The results also show that the design of retaining structure of foundation pit is scientificand reasonable, monitoring program design is correct, the field monitoring data are reliable.The research for future similar project construction has certain reference value and guidingsignificance.