The Finife Element Analyse On Foundation Excavation By Steps And Affection Factors Of Pit-Retaining Structure Deformation

On the basic of reading a lot of internal and external literature and summarizing the former research achievement, in view of displacement deformation and earth pressure behavior of pit-retaining structure during the process of deep foundation excavations, analyses of calculating method for excavation by steps and practical engineering measurement had been finished. Finally, using PLAXIS finite element program, displacement field, distribution of earth pressure, deformation and affection factors on pit-retaining structure had been calculated in the progress of excavation of the practical engineering. The main results can be summarized as follows:1. The design theory of pit-retaining structure was been carefully studied. The earth pressure and displacement are analyzed, including the lateral displacement during excavation , the vertical displacement caused by excavation and the rebound of foundation excavation, .in addition, the lateral load of the pit-retaining structure was considered.2. The calculation progress and method of foundation excavation by steps was been carefully studied. With the analyses of the formation of excavation loads, the calculating method for excavation loads, which was suitable for engineering practice, was put forward. Moreover, some new suggestions were given in view of excavation units, joint.3. By the systematic study on soil constitutive relation and yield criterion, the theory and function of PLAXIS finite element program were analyzed.4. In accordance with practical measurement of engineering, the calculation was made by PLAXIS finite element program for the first time, and the results were compared with practical measurement. The former tallied with the latter. It proves the necessary of excavation by steps in the design of pit- retaining structure.5. In accordance with practical measurement of engineering, the affection factors of deformation was made by PLAXIS finite element program for the first time, including factors of design , construction and natural environment. The important factors are analyzed by quantification, some useful conclusions of controlling deformation pit and saving cost are obtained through the analyzing results.In words, this paper has analyzed earth pressure behavior, deformation and affection factors of pit-retaining structure in the process of excavation by steps. The study has relative high theory and application value. It contributes to improve the structure design level and safety;moreover, it has relative high social and economic benefit.