Research On Stress Distribution In Composite Ground Improved With Rigid Piles Under Flexible Foundation

Composite foundation such as CFG pile,concrete pile composite foundation etc. is often used to improve subgrade bearing capacity in road engineering. Because of inadequate analysis in consolidation mechanism of composite foundation , a series of engineering problems such as excessive settlement and settlement difference of subgrade ,road bed sliding failure are brought out.In this thesis, additional stress and settlement in composite foundation,which are caused by loads, loads on the pile cap, side frictional stress and restraints of pile head, are developed based on Boussinesq formulas and Mindlin formulas.In this thesis, the composite foundation is divided into a certain composite cells. Each composite cell includes a certain pile shaft cells and soil cell.Under the condition of the slide between pile and soil around pile is taked into account,five equations are established, including the equation of compatibility between the settlement of pile cap soil and the settlement of pile cap; the equation of compatibility between the settlement of pile head soil and the settlement of pile head; the physical equation between the settlement of soil around pile shaft and the settlement of pile shaft;the equation of equilibrium between loads on the pile cap, side frictional stress and restraints of pile head; the equation of compatibility between the deformation of the pile body and the subtraction between the settlement of pile cap and the settlement of pile heap.With iterative calculation method, loads of pile cap ,side frictional stress, settlement of pile cap, settlement between pile and soil,are deduced in condition of a group of initial side friction coefficients.The calculation model is used to the composite foundation of a bridge approach. Comparisons with the gauged resultants of road bed settlement and the computering resultants show great identical.The method may be referenced in engineering designing.The coherence of the gauged resultant and the computering resultant shows that the model can be used to analyse the stress distribution in composite foundation and the...