Consolidation Analysis of Column–Reinforced Composite Ground Considering Load Transfer Characteristics

ABSTRACT The flexible deformation characteristics of granular and accumulated embankments result in a relatively weak lateral load transfer capacity, requiring sufficient differences in column–soil settlement to transfer loads from the surrounding soil to the columns. Although large‐diameter columns improve the load transfer ability, not only vertical deformation but also vertical and radial flow occurs inside the column during the consolidation process. To address the consolidation problem of this column–reinforced composite ground, a modified equal strain condition is proposed to consider the difference in settlement between the column and its surrounding soil, and a load transfer‐resistance coefficient is used to represent the lateral load transfer ability. On this basis, the consolidation equations considering the vertical deformation and vertical and radial flows of the columns are established. The analytical consolidation solutions under time‐dependent vertical stress are obtained through the separation of variables method. When the modified equal strain condition is simplified to the equal strain condition, the analytical solution under instantaneous loading in the paper simplifies to the previous corresponding solution. In this case, the concentration region (column or surrounding soil) of the initial pore pressure relies on the vertical permeability coefficient rather than the compressive modulus. Under the modified equal strain condition, the concentration phenomenon of pore pressure occurs later and presents a pseudo Mandel–Cryer effect. Parametric analyses of the consolidation characteristics of composite ground beneath flexible foundations under instantaneous or ramp loading are conducted, providing reference data for design and construction.