Study On Analysis Of Settlement Calculation For Discrete Material Pile Composite Foundation

With a excellent effect on foundation treatment, composite foundation is used wildly in actual projects. Some economical composite foundations, such as gravel pile and slag pile composite foundation, are well-received by the engineers. This kind of composite foundations is called discrete material pile composite foundation. However, because pile of this kind of composite foundation is made of discrete material, under the load, pile-soil interaction is very complicated. Theory which is used to calculate settlement of composite foundation with discrete material pile can not catch up with its application. Therefore, a new method of settlement calculation for composite foundation with discrete material pile considering the different characteristics of pile body, must be established and applied in actual projects, which aims at improving the settlement theory of composite foundation with discrete material pile was proposed.In the present study, considering the pore of pile body and soil, bearing mechanism and deformation mechanism of composite foundation with discrete material pile were discussed. Then, based on above mechanism, the relationships that mechanics parameters and geometry parameter of pile body and soil varies with the applied load for the variation of the void ratio were developed. At the same time, methods to determining the mechanics parameters and geometry parameters were established, considering the variation of void ratio. Thirdly, by introducing the above relationships into settlement analysis, a new method to calculate displacement of composite foundation with discrete material pile was proposed by using the multi-stage loading and the layer-wise summation approach. This method is effective accounting for the effect of variations of void ratio on deformation of composite foundation with discrete material pile. And the corresponding flow chart of settlement calculation was established subsequently. Finally, the proposed method was used to actual composite foundation problem, whose theoretical results were presented and compared to those of other methods. The rationality and feasibility of this method were identified through comparative analysis.The method to calculate settlement of composite foundation with discrete material pile proposed in this paper, is not only reflecting the progress that multi-stage loading due to building operations affects stress and deformation of composite foundation with discrete material pile but also describing the variation of mechanics parameters and geometry parameters with the above load. Based on deformation mechanism and pile-soil interaction, using the method established in this paper to calculate settlement, compression curve and modification factor are avoided. Influence of stress history affects on mechanics parameters and nonlinear deformation of pile and soil are described while using this method to calculate settlement of composite foundation. It promotes the development of composite foundation theory, and perfects present theory to calculate settlement of composite foundation with discrete material pile.