Numerical implementation of suction-dependent resilientmodulus constitutive model for subgrade granular material

In order to investigate the suction-dependent properties of subgrade granular material and its effect on pavement responses, coupled hydro-mechanical simulations were conducted in Abaqus. A suction-dependent resilient modulus model was integrated into the commercial finite element(FE)code Abaqus by developing a user-defined material(UMAT)subroutine. The developed model was validated by triaxial test results under different suction conditions and good agreement was achieved. A three-dimensional(3D)FE pavement model was established and the suction-dependent properties of subgrade granular material was characterized by the developed constitutive model. Hydro-mechanical pavement responses subjected to three moisture states and the falling weight deflectometer(FWD)load were calculated. Simulation results reveal that the resilient modulus of subgrade granular material is sensitive to suction and stress states; high groundwater table decreases the overall resilient moduli of subgrade structure due to suction reduction, leading to the increase of the maximum surface deflection, the tensile strain at bottom of the surface layer, compressive strain on top of subgrade, and consequently, deterioration in pavement performance.