Bearing capacity of composite foundation consisting of T-shaped soil-cement column and soft clay

The T-shaped column is a soil-cement column with two diameters, which is installed by foldable deep mixing blades for soft clay treatment. As a variable-diameter column, its design method is not well established, and this study focuses on the bearing capacity of composite foundation consisting of T-shaped columns and soft clay. A laboratory model test was employed to study the bearing capacity, stress distribution, and failure mode of the composite foundation. Twelve full-scale loading tests were performed in the field to study the geometrical parameters of composite foundation affecting on its bearing capacity. The experimental results indicated that the bearing capacity of composite foundation increased with increasing of the cap length and column diameter, and decreasing of the column spacing. The experimental results also revealed that the column failure might occur at the small-diameter column just below the column cap, which then led to the soil failure nearby. By including this additional failure mode, the design method for conventional column was adapted to estimate the bearing capacity of composite foundation consisting of T-shaped column and soft clay, and the method was validated by the experimental data.