Effect of sand bed thickness on the response of concrete block pavement: a numerical investigation

This paper presents an insight into the effect of increasing sand bed thickness on the response of the concrete block pavement (CBP) subjected to vehicular loads. CBP sections with sand bed thickness of 10, 20 and 70 mm were chosen in this study. Simulations were carried out using three sets of acceleration amplitudes from vehicular movement with frequency ranging from 0 to 100 Hz under steady state modal dynamic conditions. The finite element package ABAQUS was used for the simulations. Different soil constitutive models including the linear elastic model, Mohr–Coulomb model and cap plasticity model were used to model the material behavior of the soil layers underneath the paving block layer for every case. The results were obtained in terms of acceleration and displacement responses in the frequency domain. Sand bed thickness of 20 mm was found to be the optimal case as the increase or decrease in thickness from this median value resulting in relatively higher displacement values. CBP sections with 70 mm thick sand bed accounted for higher values of vertical deflection followed by CBP section with 10 mm thick sand bed. Considerable shift in the resonance frequency was also observed for the CBP section with 70 mm thick sand bed. Further simulations using Mohr–Coulomb and linear elastic model were found to overestimate the deflection values as compared to the cap plasticity model. The numerical predictions using cap plasticity model were in close proximity with the experimental results, thus concluding it as a stable constitutive model for such applications to this end.