A CONSOLIDATION MODEL OF GROUP WELLS ON COMPOSITE FOUNDATION1)

For the consolidation problem on the composite foundation, with consideration of the influence of the well resistance and the vertical seepage in the soil radial direction, a calculation model of composite foundation group wells with pile-soil-pile as a unit is established. By using the analytical method, the analytical solution of the composite foundation group well consolidation under an instantaneous load is derived, as well as the consolidation characteristics and the pore pressure variation of the composite foundation. The study shows that the consolidation model of the composite foundation group wells provides a new idea for the theoretical study of the consolidation of the composite foundation. When the borehole diameter ratio is greater than 5, based on the assumption that the flow rates in the central pile and the side pile are equal, the difference between the consolidation degree calculated by the group well consolidation theory of the composite foundation and that calculated by the traditional consolidation theory is very small and negligible. The consolidation rate of the composite foundation increases with the increase of the pile permeability coefficient, the radial permeability coefficient of the soil in the disturbed zone and the vertical permeability coefficient of the soil. The larger the load is, the larger the settlement and the vertical strain will be. The pore pressure dissipation rate and the vertical strain rate of the surface soil are higher than those of the underneath soil.