Research On Static And Dynamic Soil-Pile-Structure Interaction Of Tall-building

For the tall-building structure has the character of complex system, enormous volume and huge weight, if it is built on the soft soil or deep soil foundation and depended on the hypothesis of rigid foundation without regard to the interaction of superstructure and base, the result will be unreasonable and cause a big discrepancy between calculation and reality. Superstructure, base and foundation are an organic whole which connect and influence each other. Static interaction needs to reasonable think about the soft reaction of foundation while the dynamic interaction also needs to think about other elements such as infinite, quantity, damp and so on. In recent years, with the ultra-high rise buildings develop rapidly, the height increases ceaselessly, the types become abundant and the system increases diversiform, interaction becomes more and more obviously. The interaction of superstructure and base has become an unavoidable key scientific question in some important projects.The spot-test for interaction of superstructure, base and foundation is one of the main investigative methods which is seldom in our country at present and is blank in loess region. For this reason, the author and collaborators has tested in spot an ultra-high rise building in Xi'an-the Building of Post and Telecommunication and Administration of Networks in Shaanxi Province to fill up this blank.Finite element method is the best efficient numerical calculation method to research interaction of superstructure and base. It's usually needed to disperse amount extent when using this method. If the piles and soil are divided respectively, the element numbers become huge which will be limited by computer software and hardware and lead to analysis unfinished. In order to settle these questions, it needs to deeply investigate some basic problems, learn force characteristic and mechanism, hold on the essence of the problems correctly, simplify analysis method which can fully grasp and show the main characteristic, build on the macro modelbased on finite element analysis and increase the model ability and maneuverability of finite element method in interaction analysis. All these work are made one of the important part in this paper.This paper is regarding one real project—the Building of Post and Telecommunication and Administration of Networks in Shaanxi Province as the research example to make spot-test of static and dynamic interaction. On the base of deeply research for simple, grouped piles forcing and distortion, the paper is looking grouped piles foundation as the composite material, establishing efficient macro analysis model and using finite element program (ANSYS) to study structure's static and dynamic interaction. The main contents and results are showing as following:(1) It has been established the base model, simulated the finite element elastic and plastic case for simple, grouped piles and deeply analyzed forced principle and distortion law of simple and grouped piles which is combined with the testing piles results of some relative work. All these have established the base of simplify computation and equivalent settlement.(2) The pile-soil system in grouped piles foundation was regarded as one kind of composite material in terms of the equivalent continuum method, on this base, the pile-soil composite material's constitutive relation and equivalent composite material model were firstly established in this paper. The results was shown that the equivalent composite material model can be reflected the grouped piles foundation's load transfer mechanism well, which largely reduces the finite analysis difficulty and explores efficient solution for the interaction between superstructure and foundation of ultrahigh-rise building's analysis in order to take advantage of finite element software. This model can be used not only in static analysis but also in the dynamic analysis.(3) It has been analyzed two kinds of unload reasons as stopping dewatering and raft concrete harden and shrinkage reflecting the pile-raft system's forced and reasonable...