Study On Simulation Analysis And Construction Monitoring Of Deep Foundation Pit

Deep foundation pit of Xiamen Metro line 1, Zhongshan park station is used as its engineering background, this paper uses FLAG3D to do numerical simulation calculation of excavation process of deep foundation pit of Zhongshan park station, and puts forward the construction monitoring scheme of deep foundation pit of Zhongshan park station and collects field monitoring data, analyzes the rules of surrounding earth’s surface of deep foundation pit, cumulative settlement of the buildings, horizontal displacement of supporting pile and axial force changes of each support, in order to indicate that the earth’s surface and volatility curve of rise and fall of cumulative settlement of the buildings in the process of excavation is associated with excavation of foundation pit and support installation. But the final result is sedimentation of the earth’s surface and buildings; Horizontal displacements of pile body, especially monitoring point whose horizontal displacement of deep foundation pit changes greatly are the direct embodiments of characteristics of retaining structure deformation, is an important indicator of evaluating retaining structure safety; Support distinctly limits the deformation of deep foundation pit, which is helpful to the structure stability of deep foundation pit. Comparison analysis of measured data and simulation calculation are carried on. In simulation analysis, maximum lateral displacement of the pile body increases with the increase of excavation depth and gradually goes down, Simulation curve is in the shape of "bow" on the whole, Horizontal deformation trend of retaining pile body gained from field monitoring is in general consistent with that gained from numerical calculation, which indicates that this paper is succeeded in using FLAC3D software to simulate the constitutive relation and design parameter fitting of deep foundation pit of Zhongshan park station. Through simulation calculation and practical monitoring in the process of excavation of deep foundation pit of Zhongshan park station, we know that the maximum displacement of pile body is above excavation face of deep foundation pit, which generally appears in the range of about 10 to 15 m in the middle of pile body. There is still a small amount of displacement near the bottom of the pile, which indicates that design method that makes built-in segment as a fixed end remains to be improved. Finally, clear distance between foundation pit piles in Zhongshan park station should be optimally calculated. Design value of clear distance between piles selected by deep foundation pit support piles is within the permitted range, and the clear distance can be increased a little more.