Study On The Counterforce On The Pile Head And The Sedimentation Characteristics Of Piled Raft Foundation And Balance Design Method For Variable-Rigidity

On the basis of investigation on the related researching achievements home and abroad, this thesis puts emphasis on studying the counterforce on the pile head and the sedimentation characteristics of the piled raft foundation under the vertical loads, considering the superstructure's effect. And then, this thesis probes into the principles, methods and processes of balance design method for variable-rigidity.Based on predecessor's achievements, this thesis has studied the intrinsic interaction mechanism of pile-pile and pile-soil in the layered soil. With the shearing deformation theory and deductive theory, the calculational formulas of flexibility coefficient of the pile head can be obtained. The interaction of the soil elements is calculated according to the layered-soil model. Consequently, approximate analytical formulas of the flexibility matrix of piles-soil system, which undertake the vertical loads, come out. Owing to this, we can also get the rigidity matrix of piles-soil system.In this thesis, there are six arguments in each node of three-dimension pole element which is used to analyze the superstructure. With the classical the slab theory, the thin and thick slab universal element, which is composed with the general harmony unit method, is used to analyze the raft, and each node has three arguments. But there is only one argument in each pile node or soil node in piles-soil system. Therefore, an effective, simple and feasible coupling method is proposed in this thesis. That is to couple the three different rigidity matrixes of superstructure, raft and piles-soil system. Subsequently, the interaction equations and its analysis programs come into being.With the applications of above interaction analysis method and its analysis programs, the following works are studied in this thesis,(1) Study on the effects of the design parameters of the slab, which affect the counterforce on the pile head and the sedimentation characteristics of the piled raft foundation.(2) Study on the effects of the design parameters of the piles, which affect the counterforce on the pile head and the sedimentation characteristics of the piled raft foundation.(3) The principles, methods and processes of Balance Design Method for Variable-Rigidity were expatiated on the basis of above studies.The theoretic studies show that the variation of span, length and diameters of piles,...