Study On Deformation Control And The Influence On Surrounding Buildings Of Deep Foundation Pit Excavation

With the development of the modern society, the pressure of ground traffic becomes larger. To ease traffic pressure while reducing the dust and noise pollution, the exploit of underground space has been irreversible trend today. Inevitably, the deformation of retaining structure and soil around foundation pit must be caused by the excavation of the deep foundation pit, which will adversely affect the safety of foundation pit and surrounding buildings. Therefore, deformation control and the protection for surrounding buildings of deep foundation pit excavation are typical technical problems in built-up areas.Taking the foundation pit engineering of Nanjing Jiangdong Road as the research objects, depending on the project supported by National Natural Science Foundation of China (51378168) and the project supported by the Fundamental Research Funds for Central Universities (2012HGZY0024), a whole 3D model considering the soil-structure interaction by using three-dimensional numerical simulation was established based on MIDAS/GTS. The main research contents are as follows:(1) Taking the foundation pit engineering of Hanzhong Gate as the research object, internal force and displacement variation of the envelope was found by analyzing axial force of the foundation and internal forces as well as displacements of the envelope using three-dimensional numerical simulation. Furthermore, the accuracy of the numerical simulation was verified by means of comparing calculation results with monitoring data. Through the study of the deformation excavation, some control measures to reduce the displacement of retaining structure were put forward which was confirmed by numerical simulation using finite element software and obtained the most effective method of controlling the deformation.(2) Taking the foundation pit engineering of Qingliang Gate as the research object, found that the calculation model could effectively predict deformation of retaining pile, supporting axial force of foundation pit along with settlement influence on surrounding buildings and a strong relevance were proved between the settlement of surrounding buildings and supporting axial force as well as lateral deformation of building envelope by using three-dimensional numerical simulation which was compared with monitoring data. Meanwhile, the rationality of foundation design and excavation scheme was demonstrated which may provide the basis for the design and construction of related engineering in the future.(3) Combining with Engineering Practice, environmental problems caused by excavation of foundation pit were analyzed and put forward a series of protective measures; monitoring data of foundation pit was analyzed systematically which can guide the construction opportunely.