The Interaction Of Upper Structure-raft Foundation And Foundation Optimization

With the development of social economy and the progress of science and technology, high building is developing very rapidly, and in the process of designing high-rise building, the foundation of the analysis and design is a very important step in the whole structure design of high-rise building. Thus with the advancement of the numerical calculation method and the computer technology, the application of the analysis method in the design of building foundation becomes necessary. So this paper undergoes an analysis of the interaction between the frame structure-raft foundation and the natural foundation, based on this, using the method of changing foundation to partially alter the stiffness of foundation so that optimize the design of foundation.This paper(?)ses the finite element software ANSYS to establish the frame of structure-raft foundation and natural foundation and conducts an analysis. Specifically, in the process of this research, this paper mainly do the following:(1)First, this paper introduces the development of raft foundation of high-rise building on natural foundation, summarizes the raft foundation of several calculation method, and sorts out several optimized forms of the foundation according to settlement controlled design. Then, it introduces the mechanism of interaction and the stiffness of the influence among the three factors, the method of method-substructure is used in analyzing the interaction, and introduces how to choose the model of the foundation.(2)Setting up the interactional model and the conventional model, compared the internal force redistribution of the upper structure and internal force and deformation of foundation of two analysis methods, and compared it with theoretical analysis. Change the stiffness of the upper structure, raft foundation and foundation respectively, and then research the affection caused by respective changed stiffness on stress and deformation of raft foundation.(3) Using ANSYS element of birth and death technology to carry out simulate construction, and analyzing the influence of upper structure stiffness on the settlement of distribution and stress of raft foundation.(4)Make use of the interactional model, and change foundation stiffness in depth and plane according to the controlled settlement in order to find a optimal solution scheme and to Compare settlement distribution of raft foundation, the force distribution and stress of the raft among several typical treatment schemes.From the above, there comes a conclusion:a. compared with the conventional method, the application of interactional analysis method on calculating the stress and deformation of raft foundation all decreased significantly. It explains that the interaction analysis method can reflect the work field structure state more accurately, b. Increasing the stiffness of the raft foundation can effectively reduce the differential settlement and optimize the stress of the raft foundation; Increasing the stiffness of the foundation integrally can reduce the base settlement peak, but has little influence on reducing differential settlement, c. undergoing interactional analysis through simulating construction, from which it can find that increasing the stiffness of the upper structure can reduce local overall bending and stress of raft foundation, but its contribution is not unlimited, so we should effectively use the stiffness of the upper structure, minimize the size of the foundation; d. The settlement distribution of raft foundation is more balanced, and the stress of raft is reduced obviously after the optimization of the foundation, which shows according to the controlling of the settlement, the change of the local stiffness of foundation has remarkable significance.