Application of subgrade treated by dynamic compaction in old road rebuilding

Based on the introduction of the reconstruction and extension projects of Dacheng-Wanzai section of No.320 national road in Jiangxi,the paper effectively eliminates the subgrade defects by using the dynamic compaction technology,the appropriate selection of the parameters and treating the copula between the old and new subgrades according to the problems that the sliding and the settlement of the new subgrade are produced because the old and new subgrades do not tightly connected in the widening parts of the subgrade of the old road rebuilding,which achieves the good results.