Stiffened deep mixed (SDM) column is a new ground improvement method for soft soil foundations

and has been successfully applied in ground improvement projects in roadways and railways recently. However

due to inadequate understanding of the instability mechanism of the embankment supported by SDM column

there is no mature theory to guide the design. In this paper

strain-softening model

which can reflect the post-failure behavior of column materials

was used to model the scale-down 1g model test of stability of SDM column-supported embankment. The sequence and modes of SDM column failure were investigated through examining the developments of plastic zone and force changes in SDM columns in the failure process. The results showed that the columns did not fail simultaneously in the process of embankment failure. The columns near the center of embankment failed by compression at first

followed by the sequence bending failures of the columns under embankment slope from the toe to the shoulder. The slip surface did not completely pass through the failure positons of the columns due to the existence of columns. Accordingly

the failure mechanism of SDM column-supported embankment was interpreted. The semi-rigid column method based on residual strength in the currently-used code yielded close factor of safety to the model test

but its feasibility still needs a further study.