The Mechanism Analysis Of The Geosynthetic-Reinforced Pile Supported Embankment

Geosynthetic-reinforced and pile-supported (GRPS) earth platform has been emerged as an effective alternative successfully adopted worldwide to solve many geotechnical problems ,especially in the soft foundation of embankment , however, its theoretical research is apparently far behind engineering practice.Pile-soil stress ratio is basic notion and calculation index in composite foundation; it points out pile and soil stress distribution, and it need be used both in settlement and bearing capacity calculation. According to the composing of the pile-net composite foundation, reducible model of composite foundation is established ; then based on force balance condition of net unit and the characteristics of embankment loads, the formulas of pile-soil stress ratio and post-construction settlement are deduced; at last, main factors that influences pile-soil stress ratio and its rules are analyzed quantificationally .For further studying bearing performances rules of pile-net composite foundation by using the finite element method (FEM) software of ABAQUS. Prior to parametric studies, then numerical model was verified using an engineering case in Finland. The final results accorded with field test fairly well and the error were less than 10%, which show the reliability of proposed numerical mode. Combining with the each property of different modulus pile and geosynthetics, a basic model for geosynthetic-reinforced and pile-supported earth platform composite foundation which used pile was built and the basic characteristics of composite foundation were discussed on the base of numerical results. From numerical analysis under kinds of different calculating condition, the stress and deformation behaviors of composite foundation were investigated under the influnce factors of the elastic modulus of pile, the elastic modulus of soft soil, the tensile stiffness of geosynthetics, the different height of embankment ,the gapped pile foundation(with a gap between pile head and cushion). Then numerical results were examined in terms of the maximum and differential settlements at the base and on the crest of the embankment stress distribution and stress transfer between pile and soft soil, and tension developed in geosynthetics.