Study On The Laws Of Different Settlement Between Diaphragm Wall And Column As Well As Between Columns In Deep Foundation Pit Constructed With The Top-down Method

With the rapid development of the domestic economy environment,the development of the Hefei area is rapid as well,the construction of large scale civil buildings,commercial buildings,public buildings are in full swing.In general,the larger the size of the building,the larger the size of its foundation pit.When the foundation pit in these conditions that complex surrounding environment,irregular shape and special geological condition,the difficulty of construction will be greatly improved and the construction technology will be put forward higher requirement.The deformation law of the retaining structure and surrounding soil of this kind of foundation pit will be different in a certain degree,compared with the general foundation pit,such foundation pit has more research significance.In this paper,the deep foundation pit engineering of Hefei Xin Jiao Tong building is studied as the research background.The deep foundation pit is located at the junction of metro line 1 and line 2,which the diaphragm wall of the two metro station is used as the building foundation pit’s diaphragm wall,and this construction environment is complicated.By consulting relevant data,comparing the results that the finite element software MIDAS GTS/NX analysis with the result of monitoring data,It focus on researching the differential settlement laws between diaphragm wall and column as well as between columns,and the deformation laws of the lateral displacement of diaphragm wall and ground settlement are also researched.The purpose of this paper is to guide the similar projects,and the main work and the conclusions are as follow:1.Summarize the results that researches on excavation and analysis the deformation mechanism of underground structure and soil as well as the construction principle and advantages of Top-Down method.2.When the Top-down method is used,the differential settlements between diaphragm wall and column as well as between columns are small,the maximum differential settlement values are much less than 20 mm or 1/400 column spacing,so the differential settlement can be well controlled by Top-Down method.3.The differential settlement and the structural stiffness is closely related,and the differential settlement has an inverse relationship with the structural stiffness.So,In the construction process,the settlement of column that stand by the excavation port and the side of the foundation pit of the subway should be paid more attention,and the support can be properly increased when it necessary.4.Within a certain range from the foundation pit edge,the ground settlement first increased and then decreased,the settlement curve is “scoop” shape.Along with the foundation pit excavation,the position of the maximum lateral displacement of diaphragm wall move down gradually from the top of the wall,and finally presents the "bow" shape of that is big in the middle but is small at both ends.5.The results from comparing simulation with monitoring analysis shows that simulation results are close to monitoring’s,although there are numerical deviations,the overall change trend is similar to each other,thus testing the validity of the numerical simulation.