Parametric study of reinforced pavements on soft clay under traffic loading

A parametric study was carried out to evaluate the beneficial effect of geogrid reinforcement in the pavement under traffic loading considering softening behavior of clay.Firstly,cyclic triaxial tests were conducted to investigate the effect of initial deviator stress,loading frequency,overconsolidation ratio,and cyclic stress ratio on softening behavior of clay.The empirical equation for softening of clay was proposed by regression analysis method.The equation was imported into FEM program ABAQUS through compiled subroutine.A series of finite element simulations were carried out to investigate the beneficial effect of geogrid reinforcement on the vertical displacement,and how such effects were influenced by the loading forms,loading frequency,geogrid modulus,geogrid location,geogrid layers and subgrade thickness.It was indicated that the greater the loading frequency was,the less the beneficial effect of geogrid reinforcement was.With the increase of geogrid modulus and geogrid layers,the effect of reinforcement increased.Among the three locations examined for the geogrid reinforcement,the best location which resulted in the highest reduction in the value of vertical displacement was at the bottom of pavement.For small subgrade depth,the effect of reinforcement significantly increased with the increase of subgrade depth.But for large subgrade depth,the effect of reinforcement did not significantly increased with the increase of subgrade depth.