Finite Element Simulation Analysis Of Super Large And Deep Foundation Pit In Tianjin Yujiapu

With the development of urban construction in China, the scale of the excavationengineering are becoming deeper and greater. Based on consulting a large amounts ofliterature data, researching and learning about the research progress and the basicprinciples of the excavation engineering, the writer makes a research for the TianjinYujiapu oversized deep excavation engineering which is400meters long and250meters width in the following aspects.⑴With the background of a practical engineering and the use of finite elementanalysis method, the article proves that the way that reinforced concrete piles aremodeled as underground enclosure piles in accordance with the principle of equalbending stiffness is applicable in the finite element analysis. At the same time, theapplication of residual stress factor in the pit proves the importance of considering theresidual stress in the numerical simulation of the deep foundation pit engineering.⑵The numerical simulation and the measured data show that the horizontaldisplacement of the retaining structure working together with the yin corner and yangcorner of the pit present a space characteristics. At every location, the horizontaldisplacement between the yin and yang corner is the minimal, and from this positionto the both sides tends to increase. And, in the corner of the pit, the top displacementof the yin corner is less than the yang corner. The two yang corners in this deep andlarge foundation are both father to one side and closer to the other side.⑶The support system is generally in axial force state after the pig excavation.Bending moment of the truss bar at the foundation corners and the both ends of thebraces is bigger. After the support application and the second earth excavation, theshape of pile sway was like a bow. The excavation caused the further development ofthe pile. The largest point of the pile sway appeared10meters below the top of thepile. For large pit in the article, the space effect will be very weak in the middle of thepit, which should be pay attention to for the big development of pile sway.⑷The article also proved that the use of numerical analysis can simulate thesurrounding surface subsidence trend detailed. With the increment of the excavationdepth, the sphere of influence on the surrounding surface subsidence is also gradually increasing. And the maximum of surrounding surface subsidence maximum also tendto increase, which is6to10meters away from the pit wall.