| As a kind of the flexible supporting structures, the steel sheet piles are widely used in retaining and protecting for foundation excavation, bridge cofferdam construction,river bank protection and ports. It has lots of advantages, such as light weight, high strength, durability, water tightness, high construction efficiency, environmental protection, recycling and other unique advantages. Steel sheet pile retaining structure is mainly connected together by the interlocking joints along the pile body direction as a whole structure of retaining wall, which is subjected to the loads of soil and water pressure acting on the pile walls.However, the domestic and foreign researches discovered that U-shaped steel sheet pile which is most widely used in the practical engineering, has the phenomenon called“Reduced modulus action”. The working mechanism of steel sheet pile supporting structure and interaction between piles and soil are not clarified, as well as the design theory and calculation method of the steel sheet pile support support are currently in a semi-theoretical and semi-empirical immature stage, so we need to study on carrying out depth and systematic theoretical analysis and numerical calculation, to further improve the practical engineering design methods of steel sheet pile retaining structure.On one hand, the different friction to the interlocks of steel sheet pile directly influence the transmission of shear forces in steel pile interlocks, thus resulting in the stiffness reduction effect to pile wall, which makes the internal force and deformation calculation results to the design of steel sheet pile supporting structure are difficult to be accurate. On the other hand, with the development and utilization of urban underground space, steel sheet pile retaining structure gradually replaced parts of the traditional forms of the supporting structure, while the working mechanism, load transfer law, and the mechanism to the deformation of supporting structure and the instability of foundation pit is not very clear and needs to be explored further. In this dissertation, the mechanism of steel sheet pile support structure and the reduction effect caused by the friction to interlocks, the internal force and deformation behavior of supporting structure,as well as the stability of foundation pit were investigated. The main research work done in this thesis consists of the following parts:1.Analyzed the characteristics of steel sheet pile in practical engineering, pointed out that the measures of lubrication and seepage control how to influence the frictioncharacteristics of steel sheet pile interlocks in the actual engineering, and locking friction how to change shear transfer state, resulting in Reduced modulus action.2.Elaborated the application of ABAQUS software in geotechnical engineering,introduced two kinds of constitutive models of soil: Mohr-Coulomb and Drucker-Prager,and compared the applicability of these models.3.Carried out numerical simulation analysis of the classical foundation pit cases which was based on the reduced modulus action of steel sheet pile retaining wall, the design theory of steel sheet pile supporting structure for foundation pit and the finite element numerical analysis principle, in order to focus on the influence degree to the safety and reliability of steel sheet pile supporting structure due to the friction characteristics of the interlocks, and inquiry the working mechanism of sheet pile foundation pit support, as well as study the change in the process of the internal force and deformation of supporting structure and the stability of the foundation pit.4.Verified the feasibility of finite element simulation, and provided references for the similar design of support engineering, by carrying out the numerical simulation of support engineering for the underground garage of Guxiwan Commercial Plaza with the finite element software-ABAQUS. |
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