Coupled vibratory roller and layered unsaturated subgrade model for intelligent compaction

To provide theoretical guidance for intelligent compaction, this study proposes an efficient analytical model that considers the coupled dynamic interaction between a vibratory roller and a layered subgrade. The vibratory roller is simulated using a lumped parameter model, while the subgrade is characterized as a layered unsaturated poroelastic medium. The governing equations are solved using the double Fourier transform to derive the steady-state solution of this fully coupled model. The correctness of the proposed model is verified by comparing it with published analytical results and field test results. Results indicate that the vertical acceleration response of the roller drum is sensitive to variations in subgrade modulus. However, when evaluating the modulus of the current filling layer, it is crucial to consider the effects of the underlying layer on the acceleration response of the roller drum, especially when the existing subgrade thickness is less than 2 m. The influence of excitation frequency on the sensitivity of vertical acceleration response is found to be significant. For subgrade quality assessment with existing subgrade thickness less than 2 m, a low-frequency excitation load is recommended to maximize sensitivity, while both low and high excitation frequencies can be employed for thicker existing subgrades.