Dynamic Mechanical Behaviors of Soil under Impact Loads

The test of the impact characteristic of soil is made on split Hopkinson pressure bar at various strain-rates. The dynamic mechanics properties and the strain-rate effect of soil are discussed. Based on the characteristics of measured dynamic stress-strain curves, as well as preparatory simulation, a new viscoelastic damage model has been introduced. A linear spring is put to parallel to two Maxwell units with different relaxing time to express distinct plastic flow. In the constitutive model, one Maxwell unit with low relaxing time is used to describe the low strain-rate response of soil; and the other one with high relaxing time is used to describe the high strain-rate response of soil.Simulated stress-strain curves using the model is of good consistency with measured curves, and the simulated parameters indicate that the response of the low strain-rate of soil is just the same as that of concrete. Howevwe, the response of the high strain-rate of soil is much more violent than that of concrete.