Study on dynamic compaction characteristics of gravelly soils with crushing effect

The dynamic compaction method is one of the most optimal technics in gravelly soil backfill projects. However, the basic mechanical characteristics of gravelly soils and mechanisms of dynamic compaction have not yet been precisely determined. In this study, by taking the advantage of large-scale triaxial tests, it could be seen that gravelly soils did not present strain-hardening phenomenon like other conventional soils. Additionally, the particular behaviors of gravelly soils, i.e., increase in cohesion and decrease in the internal friction angle, were determined from grain crushing tests and large-scale direct shear tests. On this basis, a modified constitutive model was established and programmed in FLAC3D under the framework of the Mohr-Coulomb criterion. Compared to a similarity simulation test, a more accurate constitutive model considering the kinematic hardening effect was developed. Finally, a 3D model was built, where the proposed modified constitutive model and numerical parameters led to a satisfactory optimized analysis of gravelly soil projects.