Flexible Basis Pile Composite Foundation Traits And Engineering Applications

Artificial foundation composite foundation is composed of original soil and reinforcement, which soil is strengthened or replaced or installed reinforcement during natural foundation being improved or treated process. In practice, the vertical reinforcement composite foundation is usually called pile composite foundation for short. With the pile composite foundation more and more applied in the soft foundation treatment of road, there have been more different behaviors of pile composite foundation between under embankment and under cement-power-spray, which is caused from different foundation rigidity. In order to conveniently research, pile composite foundation under embankment is called pile composite foundation under flexible basement.In this paper, the behaviors of a new type composite foundation (pile composite foundation under flexible basement) were systematically studied by means of model hypothesis, theoretical analyses, numerical analyses and engineering application. The main contributions are as follow:1. Hypothesized the model of pile composite foundation under flexible basement, analyzed the bear's transfer mechanism and deformation model of composite foundation, and put forward the importance of researching settle deformation of reinforced region. Analyzed the stress-strain relation of pile and soil by the stress ratio, deduced the vertical deformation and harmony equation, introduced the analysis means of deformation and stabilization.2. Numerical simulation had quantitatively analyzed the factors influencing the position of equal subsides, the pile-soil stress ratio, and the distribution of pile-soil stress. The analysis indicated: the rigidity of base and underlying stratum had more influenced the behaviors of deformation and stress.3. Based on elasticity theory and static balance theory, the friction force of pile-side of composite foundation had been analyzed though building model, and deduced analytical formulas of the friction force ofpile-side, which have some valuable reference for theoretic analysis and engineering practice.4. The deformation which caused by pile stab into basement or cushion was analyzed. Based on supposing under-layer soil being ideality elastomer, this paper has analyzed the stress distributing of soil cell under pile bottom, and considered the effect of the stress distribution of pile-downside soil, the radius of pile, the character of soil cell, and deduced the formula of stab deformation of the pile bottom piercing into under-layer. Further more, this paper has discussed the effect degree of diverse complications. It has some reference value for the optimize design and research of composite foundation.5. Analyzed the effect the function mechanism of the dry crust to bearing capacity and settlement of the composite foundation. Inquired the model of pile composite foundation under dry crust. The stab deformation of the pile had been contrasted between experimental results and theories calculation.