The Investigation On The Stiffness Of Foundation In Interaction Of Superstructure-Raft Foundation-Soil

Superstructure, foundation and soil interact each other. It is a very important problem to study this interaction in geotechnical engineering. Since Dr G.G.Meyerhof put forward the equivalent formula to calculate the stiffness of tabulate frame structure approximatively in 1950's, some scholars have resolved a lot of problems about interaction puzzling people in practice. Because the very difficulty to simulate the structure-foundation-soil interaction in lab, so the simulate way by computer is a very useful method. The computer technology is developing whip and spur, some Finite Element Method Program, using in practice widely, has been developed.Compare with the converse floorslab method , the pith of normal design principle and analysis method is displacement compatibility condition. It means, not only the equilibrium of force but also the compatibility of displacement should be taken into account at the interface between foundation and soil.Compare with normal design principle and analysis method, the advance interaction analysis isdisplacement compatibility condition and the equilibrium of force equations at the interface between not only foundation and soil but also between structure, foundation and soil.As great strides in the development of computer technology have taken place in modern time, some Finite Element Method Programs come out in succession and got the application in engineering practice. In the text, firstly, the author gives an in-depth and meticulous analysis to an eightfold space frame structure in settlement of soil, reaction and internal force of foundation and internal force of column by using ANSYS Program, which proves that it is possible to simulate the interaction of Space frame superstructure-Raft homogeneity nonlinear elasticity soil by this software. Secondly, the author provides the analysis, comparison and discussion between the conventional ways and interactive ways, which reveal the interaction influences and the internal relations on the condition that displacement compatibility and the equilibrium of force. Finally, the author emphatically investigates the influence from the stiffness of soil, the stiffness of foundation and the stiffness of superstructure equations to in settlement of soil, reaction and internal force of foundation,internal force of column and give some reasonable advice to the design and construction of high-rise according to the analysis results.