Deformation Analysis Of Vertical Enclosure Structure With Top-down Method

In Hefei new traffic building as the background, the problem of inverse advantages and disadvantages, the domestic and foreign development of top-down construction types and characteristics, principles and construction of deep foundation pit, the main existing problems, and top-down deep excavation numerical simulation research status were summarized. Analysis of deep foundation pit in the excavation process of vertical retaining structure, the bottom of the foundation pit and the surrounding surface deformation mechanism; To investigate the earth pressure of the categories and research methods and foundation pit retaining structure of the earth pressure distribution regularity and the foundation support mechanism of theoretical calculation, to for Hefei new traffic building top-down pit excavation provides some guidance in theory and construction.(1)Hefei new traffic building is located at the intersection of Hefei subway Line 1 and line 2, and Hefei new traffic building foundation pit close to Hefei subway line 1 and line 2. In addition, the new traffic building not only buildings around the situation is very complex, and large area of deep foundation pit excavation, therefore,the excavation of the foundation pit is difficult and it has high demands. Using the large-scale finite element analysis software MIDAS / GTS building foundation pit excavation of the whole process of dynamic simulation and finite element software simulation derived data and the measured data were compared and analyzed, mainly has the following conclusions and insights:(2)Inverse practices of large and deep foundation pit excavation surrounding ground settle plift and rebound. And the bottom of the foundation pit soil uplift and rebound showed small middle large on both sides. The whole shape of the spring and the bulge is like a small hill with a slight bulge.(3)In the process of foundation pit excavation, the underground continuous wall with the continuous unloading of soil has been a certain degree of deviation of deformation and uplift. First of all, the underground continuous wall of the vertical uplift with the increase of the depth of the excavation and increase the uplift displacement. In the second place, the horizontal displacement of foundation pit is alsohappened in the foundation pit, and the horizontal displacement of the underground continuous wall is increasing with the increasing of the foundation pit depth. The maximum displacement of the underground continuous wall of the foundation pit is located at the middle position of the foundation pit depth. Finally, large top-down method horizontal displacement of the long sides of the deep foundation pit deformation is bigger than the short side of the horizontal displacement deformation.In the process of deep foundation pit excavation, both in X direction and Y direction the effective stress of the whole underground continuous wall, increases with the increase of excavation depth.(4)In the process of deep foundation pit excavation, the effective stress of the whole underground continuous wall, both in X direction and Y direction, increases with the increase of excavation depth.