Bearing Characteristics And Finite Element Analysis Of Composite Foundation With Rigid-flexible And Long-short Piles

The application of composite foundation with rigid-flexible and long-short piles is becoming more and more popular in practical engineering. The design and its reasonable evaluation of such kind of foundation have been deeply concerned by engineers. However, quite few papers were represented on basic mechanism and engineering characteristics of this foundation. Perfect theories and numerical methods have not yet been formed. In this paper, in order to study the bearing characteristics and interaction of composite foundation with rigid-flexible and long-short piles under vertical load, this paper is collected plenty of data about composite foundation with rigid-flexible piles. According to current research and practical need, this paper is studied from the academic and practical point of view, and completed several things such as:First, combined with previous experience and results, then showed the status of the composite foundation with rigid-flexible and long-short piles, and the existing soil stress ratio of the composite foundation, and the research results of total settlement is analyzed.Second, working mechanisms of long-pile, short-pile and cushion are analyzed under vertical load. The analysis model of load sharing character was set up according to coordinated actions of long-pile, short-pile and cushion. With this model load transferring differential equation was made by adopting certain supposes. Then the analytic method of load sharing ratio of long-short pile and soil foundation and total settlement of the foundation are derived.Finally, The stress and displacement field characteristic of composite foundation with rigid-flexible and long-short piles is analyzed by Midas FEM,the influence of some parameters is analyzed by using Midas FEM , such as load, the elastic modulus of the cushion, the elastic modulus of the long-pile and the short-pile, to load sharing ratio of long-short pile and soil foundation and total settlement of the foundation. Stress distribution rules of long and short pile are derived at composite foundations with rigid-flexible and long-short piles.