Consolidation analysis of composite ground with stone column using a composite column-soil element model coupled seepage characteristics

Based on the permeability tests of soil-stone mixtures, a composite column-soil element encompassing the deformation and seepage characteristics of soil-stone mixtures was established by deploying the composite element method. This simplifies the complexity of finite element analysis for group column composite foundations, thereby retaining the column spacing, complex deformation, and seepage characteristics between columns and soil in the analysis. The accuracy of the formulated model was corroborated using the results of in-situ core sampling and load tests of vibro-replacement stone columns by considering the calculated outcomes of the consolidation model, developed using the composite column-soil element method for multi-column composite foundations. In addition, the influence of the depth of stone column installation, the soil content within the columns, and the amount of free gravel on the consolidation characteristics were examined via detailed computational analysis. The results indicate that the maximum lateral displacement of the natural soil foundation lessened from about 15 mm to 8 mm following the installation of stone columns. When the column depth was 30 m, the consolidation degree approached 52 % after six days of loading. The overall consolidation drainage rate was satisfactory, with a 15 % soil content within the columns. However, drainage performance was completely lost when the soil content increased to 25 %. Also, the amount of underlying free gravel posed minimal impact on the load-bearing and consolidation functions of the columns.