Abstract: The performance of a cushion layer with a thickness of 0.6m to 1.2 m over the rigid column improved soft soil layer is numerically simulated by using ABAQUS software. The cushion thickness on the stress ratio in the soil-column system and the settlement characteristics are evaluated. The results indicate that with the increase of cushion thickness, the foundation settlement increases, and the column-soil stress ratio decreases first and then increases slowly. When the cushion thickness is one meter, the column-soil stress ratio is the smallest, and this thickness is the optimal cushion thickness. Therefore, the use of large thickness cushion in the rigid column composite foundation for the soil improvement of thick, soft soil area can effectively reduce the stress ratio of foundation column to soil and the soil contribution to the bearing resistance could be fully utilized.

Key words: Cushion Layer, Numerical Simulation, Rigid Column Composite Foundation, Foundation Settlement, Column Soil Stress Ratio