Consolidation Analysis Of Multi-element Composite Foundation With Single And Bidirectional Seepage In Radial Direction

Compared with the traditional single type composite foundation,the multiple composite foundation is different in the structure,the drainage capacity,the layout and the mechanical properties of the pile,making the consolidation theory of multiple composite foundation not only derived from the traditional consolidation theory of composite foundation but also different from that of the traditional foundation consolidation theory.In this paper,in view of the characteristics of the existing multiple composite foundation consolidation theory,a multiple composite foundation consolidation model,which can consider various types of pile wells,is innovatively proposed to solve the consolidation theory of the four element foundation of the pile,such as the permeable pile,the drainage well and the impermeable pile,including the soil.On the analytic solution.According to the difference of permeability between pile and soil,the model is considered to have radial unidirectional or bidirectional seepage.It can handle pile and well combinations with different drainage capacity.At the same time,this paper adopts the method of consolidation of pile body to consider the vertical seepage and compression deformation of high displacement permeable pile to solve the influence of large pile diameter pervious pile to the consolidation of multiple composite foundation,considering the well resistance effect of pile well,and the consolidation shape analysis of various pile wells is carried out,the main work is done.And the results of the research are as follows:(1)Through the analysis of the water body of the plastic drainage plate and the bulk material pile,this paper proves that the divergent and convergent seepage models produced by different methods of unit division have no effect on the calculation results.The results show that,for the size effect of drainage body,the speed of consolidation of multiple composite foundation is dependent on the drainage area at the top of draining body rather than the section shape.The influence of drainage area at the top of drainage body on the consolidation of foundation will be more and more significant with the increase of permeability coefficient of drainage body.(2)Due to the compression deformation of the bulk material pile body itself under the external load,and the pile body has the barrier effect on the seepage,the traditional consolidation theory of multiple composite foundation will overestimate the consolidation velocity of the foundation,which is mainly because the traditional multiple composite foundation neglects the pile body deformation and the pile body radial well resistance.The results show that the larger the pile diameter or the smaller the radial permeability coefficient,the greater the difference between the two calculation methods.(3)In order to simplify the calculation,the traditional composite foundation usually treats the weak drained pile as a non perspective pile,and considers that the deformation of the weak drained pile is elastic deformation.In fact,the deformation of the weak drained pile is due to the discharge of water in the pile.The results show that the loss of the drainage capacity of the weak drainage pile will overestimate the consolidation speed of the foundation,and the difference in the calculation will become more and more big with the increase of the displacement rate of the weak drainage pile in the foundation.(4)Different types of pile and well combinations will inevitably have different drainage capacity combinations,which will inevitably lead to radial bidirectional seepage in the soil.The elastic moduli of different piles will also be very different.In this paper,the consolidation theory of composite multi composite foundation with different drainage capacity is put forward,new boundary conditions are introduced,and the influence of elastic modulus of different piles is considered,and the corresponding analytical solutions are given.The results show that the consolidation velocity of multiple composite foundation is influenced by the osmotic absorption of two drainage bodies and the drainage area at the top,but mainly depends on the type of drainage body with strong drainage capacity.The increase of elastic modulus of any pile will accelerate the speed of foundation consolidation,but the effect of consolidation on the foundation is mainly dependent on the type of pile with larger elastic modulus.(5)There are four types of drainage bodies,such as water permeable pile,weak permeable pile,low permeable drainage pile(well),high permeable drainage pile(well),and so on.In this paper,a multiple composite foundation consolidation model which can fully consider various types of pile wells is proposed,and the analytical solution of the consolidation theory of four element foundation,including soil,is solved.Through the difference of parameter values,the model can be degenerated into a variety of consolidation models,such as the one dimensional consolidation model of the Tai Sha based,the traditional consolidation model of sand well,the combined impermeable pile model of the permeable pile and the combined model of two different drainage capacity Pile wells.This study makes the consolidation theory of multi element composite foundation more practical.