Study And Analysis Of The Interaction Among Tall Building Superstructure, Thick-raft And Soil

With the increase of height of tall buildings in our country, the thickness of raft become larger and larger when raft foundation or pile-raft foundation is adopted. Owning to lack of research on properties of thick-raft foundation, the appropriate designing principles and calculation methods are lacked in engineering field. Instead the traditional design methods that lack accuracy are used in designing thick-raft foundation. It usually results in too thick raft, and makes the cost of foundation very high.In this paper, on the base of the interactive principles of superstructure, base and soil, a computation method of thick-raft foundation is brought forward in which many factors are considered. The method corresponds to real foundation working conditions. By research done on a structural model with numerical calculation method, the effects of some factors, such as superstructure stiffness, thickness of raft, compressive modular constant of soil, suspended width of raft and raft concrete intensity, on the working behavior of thick-raft foundation are analyzed. And in coordination with data obtained from an engineering test on site, the regularities of foundation settlement and the distribution properties of pile reaction, soil reaction and steel stress in raft, of the pile-(thick)raft tested are analyzed. In the same time, the calculating results with finite element method almost correspond with measured results.And in the paper, the optimized design proposals of raft foundation and pile-raft foundation are presented, which can make the raft become thinner and the cost of foundation can decreases much more.