The Numerical Analysis Of Mechanism Of Geosynthetic-reinforced And Pile-supported Earth Platform Composite Foundation

Geosynthetic-reinforced and pile-supported (GRPS) earth platform has been emerged as an effective alternative successfully adopted worldwide to solve many geotechnical problems, however, its theoretical research is apparently far behind engineering practice. Using numerical software FLAC based on finite difference method, a two-dimensional plane strain model for geosynthetic-reinforced and pile-supported earth platform composite foundation which used deep-mixed pile was established. From analyzing its deformation, stress and tension force of geosynthetics, the basic characteristics and function mechanism could be found.Prior to parametric studies, the 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 model. Combining with the each property of deep-mixed pile and geosynthetics, a basic model for geosynthetic-reinforced and pile-supported earth platform composite foundation which used deep-mixed pile was built and the basic characteristics of composite foundation were discussed on the base of numerical results. From numerical analysis under fifty-six kinds of different calculating condition, the stress and deformation behaviors of composite foundation were investigated under the influence factors of the elastic modulus of deep-mixed pile, the elastic modulus of soft soil, the tensile stiffness of geosynthetics, the spacing of piles and the layer number of geosynthetics. The 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. In addition, the maximum and differential settlements on the crest of embankment and the horizontal displacements of the toe of the embankment influenced by the introduction of geosynthetics and the average stress ratio of pile to soft soil influenced by the elastic modulus ratio of deep-mixed pile to soft soil were synthetically considered. At the end, several recommendations were proposed for the design of composite foundation based on the analytic results.