Abstract：Through dynamic triaxial test，the property of strain degradation of embankment and composite foundation is studied. Base on this，dynamic elasto-plastic FEM is used to analyze the deformation properties of road. The changing replacement ratio in the stabilized range can have impact on the deformation，and the impact can be shown mainly by the modulus. However，the impact is relatively small. As a result，while meeting the requirements of the stability and the ceiling stress of the subsoil，it is not advocated to adopt the method of increasing replacement ratio of the composite foundation to lessen the deformation of the embankment. The greatest impact on the embankment depends on the property of the subsoil，therefore，the whole soil lay may well be strengthened in the case of thinner soft soil layer. The strengthening effect may be less satisfactory when the soft soil is very thick. The changes both in the depth and the width of the stabilized range can exert great influence on the deformation of embankment，in consequence of which the deformation of embankment can be lessened through increasing the depth and the width of the stabilized range if the soft soil layer is very thick.
