Dynamic response of subgrade under impact compacted load with multiple times

The dynamic deformation and stress characteristics of subgrade under two impact loading routes with different compact times are analyzed based on three dimensional elastoplastic dynamic FEM. The results indicate that the three dimensional compressive stresses exist in the affected scope of subgrade underneath the slab. Vertical deformation of subgrade under slab corner is maximum;and vertical deformation of subgrade under slab corner is minimum. By comparison vertical deformation of subgrade,vertical deformation of subgrade is generally lower. Vertical deformation of subgrade increases with distance far away from impact point. And vertical deformation of subgrade exists obviously residual deformation,wave and hysteresis phenomenon. Vertical deformation of subgrade increases with increasing of compact times;and there exists plastic zone after the third compact time. Soil pressure increases with increasing of compact times;but increasing tendency tends to be stable. The range of increasing soil pressure is limited to certain depth of subgrade.