Contrast Research On Working Behavior Of Composite Foundation With Rammed Soil-cement Tapered Pile And With Or Without Geogrid Cushion

This paper which combined with the National Natural Science FundProject (NO.50878084) was used a technology route with a combinationmethod of indoor model comparison test and the finite element numericalsimulation. The working properties of composite foundation under differentwedge angles of rammed soil-cement tapered piles with or without geogridin the gravel cushion under flexible loads were studied. The main contentswere as follows:Firstly, comparative model test of composite foundation underdifferent wedge angles of rammed soil-cement tapered piles with or withoutgeogrid in the gravel cushion under flexible loads were carried out. Acomparative analysis of working properties for composite foundation oframmed soil-cement tapered piles was studied. It obtained that the settinggeogrid in the gravel cushion or the use of wedge-shaped pile of compositefoundation of rammed soil-cement tapered piles under flexible loads cangive full play to the characteristics of the bearing of the pile body, improvethe bearing capacity of composite foundation, reduce the differentialsettlement of the pile and soil and improve the working properties ofcomposite foundation which have a good regulating effect.Secondly, based on the shear displacement method, the Mylonakis&Gazetas model for mutual action between pile and soil, and the E.Winklerfoundation model were introduced, And then the flexibility coefficient formutual actions between pile and soil were provided. On this basis andconsidering the influence of cushion for composite foundation, ananalytical method to mutual action of pile-soil-cushion in the compositefoundation was deduced；The comparative analysis of theoretical analysisresults and experimental results of composite foundation with rammedsoil-cement tapered piles verified the applicability of the proposedapproach.Finally, the finite element analysis model of composite foundationwith rammed soil-cement tapered piles under flexible loads was establishedby the use of finite element simulation software ANSYS10.0. Thenumerical simulation analysis of the composite foundation model with rammed soil-cement tapered piles was carried out. The numericalsimulation results and measured results were compared and verified thefeasibility of the established model by finite element analysis.