Abstract: Since rigid-pile composite ground of a stable embankment deforms laterally, the rigid piles in the composite ground bear bending moment and may be cracked. The flexural capacity of rigid piles should be checked for the long-term stability of the embankment treated by rigid-pile composite ground. To reduce the difficulty of checking the flexural capacity of rigid piles in the composite ground under the embankment, the studies on simple methods for calculation of the bending moment of rigid piles are needed. First of all, the relationship between the maximum settlement and the maximum lateral deformation of embankments is statistically studied based on experimental and monitoring data of many soft ground and embankment projects of highways, and an empirical equation for the maximum settlement and the maximum lateral deformation of embankments is obtained. Then a simplified model for lateral forces of rigid piles is proposed using the lateral deformation curves of composite ground and rigid piles under embankments, and the relationship between the bending moment and the maximum lateral deformation of rigid piles is derived. The bending moment of rigid piles is suggested to be calculated according to the maximum settlement of embankments. The proposed method is proven to be simple and reasonable by an actual project. It is shown that the lateral deformation of piles is nearly equal to that of the surrounding soils, and the difference of lateral deformation between the piles and the soils can be neglected. The rigid piles can be thought to be fixed at the lower surface of soft stratum if their fixed length in underlying hard stratum is 7 times larger than their diameter.