Finite Element Analysis And Site Monitoring On Retaining Structure During Staged Excavation In Tianjin

With the rapid development of Chinese economy，the construction of urban stepsof its peak. In order to ease the pressure on urban land use and improve the urbanutilization, the development and utilization of underground space has become aninevitable trend. The deep excavation has become a major issue that must be faced inthe process of urban construction.Most deep excavation is located in the city downtown area. Deep excavation willinevitably cause the deformation of the retaining structure, difficulties and risks ofdeep and large foundation pit construction are very intractable. So, the research onsome problems such as the stability of the foundation pit during excavation and deepsoil displacement has great significance. Under the complicated geologic with weakwatery strata in Tianjin, difficulties and risks of deep excavation are intractable. Thedeep excavation of Tianjin hospital is the typical case of deep/large excavation, themaximum depth of excavation up to16.9m, and the area of excavation up to14062m2, its scale and depth is rare in district of Tianjin. Combined with Tianjinhospital deep excavation, and on the basis of summarizing the former researchachievements, relative studies in this dissertation are carried out. The contentsinclude:(1) Based on the field test for the retaining structure of Tianjin hospital, thehorizontal displacement of pile, deep soil displacement, pile settlement, columnsettlement and bracing axial force was carried out. The dissertation uses field datafrom in-site experimental studies to discuss in detail the characteristic of the force anddeformation of retaining structure, which caused by staged excavation.(2) Combined with Tianjin hospital deep excavation, the construction process ofthe deep excavation, which is under the typical geological conditions of Tianjin areais simulated with the finite element software ABAQUS. The force and deformation cause by step excavation in each construction process was analyzed through nonlinearfinite element simulation.(3) The force and deformation cause by step excavation in each constructionprocess was analyzed through nonlinear finite element simulation. By compared withfield data, the law of force and deformation of retaining structure caused by stepexcavation was obtained, and the dissertation come to some conclusions of practicalsignificance to design and construction of deep excavation.