The Upper Part Of The Pile Foundation Underpinning The Subway Tunnel Structure Of The Static And Dynamic Characteristics Analysis

As countries speea up the space or urbanization,the city disease birtn into a high-rise buildings, city Bridges and urban rail transport. With the continuous development and utilization of underground space, the subway tunnel construction with the ground has become irreconcilable contradictions, so the pile foundation underpinning arises at the historic moment. Metro tunnel is often close through the pile foundation underpinning structure, gives some adverse impact on the upper part of pile foundation underpinning structure, at the same time, when the earthquake hit structure can not damage has become a problem of concern. So how to choose the pile foundation underpinning structure and tunnel through the pile foundation underpinning structure form, understand the force of the structure, the master structure of the nonlinear seismic response time history analysis, to ensure safety, save investment, reduce cost plays an important role.To figure out the subway tunnel of the static and dynamic characteristics of the upper part of pile foundation underpinning structure, set up the operation condition of the three different conditions, using the large finite element software ABAQUS to simulate the working condition of two dynamic excavation analysis, discussed the excavation process of stress change and the vertical displacement of the bridge pile foundation; Under the action of the three conditions which are earthquake dynamic time history analysis of the pile foundation underpinning structure in tianjin wave acceleration and displacement of the structure under and forces of change. The main research contents and research results were as follows:①Analysis of the current pile foundation underpinning engineering and the research status of metro tunnel, developing direction and problems to solve, describes the implementation of the pile foundation underpinning engineering flow chart and the information construction process, introduces the underpinning structure is the main method and model of static and dynamic analysis, the analysis of the scattering effect of the tunnel method are summarized.② Simulated condition of dynamic excavation process, analysis of underpinning structure changes. Pile side friction increases obviously, pile end resistance significantly decreased; Pile foundation underpinning structure after completing system transformation, the truncated pile foundation bearing capacitv is underpinning structure. the stress of the new pile foundation is bigger than the original pile foundation; Along the longitudinal tunnel construction process, the influence of the range of about 5 times hole diameter; On the impact of tunnel excavation on the bridge displacement size sequence is:y axis> x axis> z axis.③Infinite domain boundaries in the dynamic response analysis for rock and soil were summarized, shows the importance of boundary conditions on the calculation model. Summary of the subway tunnel scattering seismic wave analysis method, it is concluded that the numerical method is more suitable for the present computational requirements.④Using the dynamic time history analysis method, analyzes three different working conditions, respectively, the acceleration time history curve of three kinds of working conditions, the peak displacement and stress of structure of the observation point. Analysis shows that the existence of the tunnel will produce certain amplification effect, and is enhanced by the tunnel as the increase of the number of. To provide a basis for structure protection measures.