Investigation of strong interlocking skeleton-dense gradation of unbound graded aggregate materials based on plastic deformation characteristics

Aggregate gradation directly affects the plastic deformation characteristics of unbound graded aggregate ma-terials (UGAMs), and improved gradation can effectively reduce plastic deformation. Firstly, the plastic defor-mation characteristics of UGAM were investigated by dynamic triaxial numerical tests, the damage strain criteria were determined, and the cumulative damage equation of UGAM plastic deformation was established. Then the influence of the gradation on the failure critical stress of UGAM was studied based on the interlocking theory, and the strong interlocking skeleton-dense gradation of UGAM is proposed. The results show that the dynamic triaxial numerical simulation method correlates well with the indoor dynamic triaxial test (the error is<5%). The shakedown plastic deformation pattern is proposed for the relationship between the axial strain of UGAM and the number of dynamic loads. The failure strain criterion that can effectively control the plastic deformation of UGAM is proposed, and the critical failure strain is suggested to be 2.5%. The proposed failure critical stress of the strong interlocking skeleton-dense gradation is 9% higher than that of the standard gradation.