Abstract: The centrifugal model tests are conducted to investigate the deformation characteristics of the river embankment on soft ground improved by the combined columnar and grid-form columns. The results indicate that reinforcing a river embankment on soft soil foundations with columnar and grid-form deep mixing columns can effectively control foundation settlement and reduce horizontal displacement, resulting in stability of high slopes. The maximum settlement occurs at the top of the river embankment, and although the settlement is not fully stabilized one year after construction, the settlement rate slows down. The significant stress concentration effects of the mixing columns accelerate the consolidation rate of the foundation. Based on measured settlement and excess pore water pressure, the degree of consolidation of the column-reinforced foundation one year after construction reaches over 80% and 75%, respectively. Due to the stiffness difference between the columns and the surrounding soil, the stress distribution exhibits stress concentration effects in the model. The measured column-soil stress ratio ranges between 2~3.