Study On Dynamic Performance Of Soft Clay And Dynamic Response Of Reinforced Pavements Under Traffic Loading

A series of undrained cyclic triaxial tests were conducted on typical Hangzhou soft clay to study the performance of soft clay under traffic loading.The FEA and semi-analytical methods were used to investigate dynamic responses of reinforced pavements under cyclic loads and moving loads.Firstly, in order to study the performance of soft clay under cyclic loading, a series of undrained cyclic triaxial tests were performed on typical Hangzhou soft clay by GDS dynamic triaxial system. The effects of initial deviator stress, loading frequency, overconsolidation ratio, and cyclic stress ratio on dynamic elastic modulus were investigated. The effects of initial deviator stress and overconsolidation ratio on degradation is significant. However, the changes of the frequencies and cyclic stress ratio have little effect on the degradation. The empirical equation for the relationship between degradation of dynamic modulus and strain was proposed by regression analysis method.Then the empirical equation was imported into FEM program ABAQUS through compiled subroutine. Dynamic response of unreinforced and geogrid reinforced pavements was studied by ABAQUS in order to investigate mechanisms of reinforcement. FEA results indicated that softening behavior of clay had visible effect on the performance of unreinforced and reinforced pavements. Geogrid reinforcement can provide lateral confinement at the bottom of the base layer by improving interface shear resistance and improve stress distribution on subgrade layer. The effect of geogrid reinforcement was also shown to reduce surface deformation and nonuniform settlement. A series of finite element simulation were carried to investigate the beneficial effects of geogrid reinforcement to the vertical displacement, and how such effects were influenced by the loading forms, loading frequency, geogrid modulus, geogrid location, geogrid layers and subgrade thickness etc..Finally, by using the homogenized transversely isotropic concept, the dynamic responses of unpaved reinforced embankment overlaying bedrock and paved reinforced pavements system subjected to moving loads were studied analytically/numerically under conditions of plane strain.For unpaved reinforced embankment, The full dynamic poroelastic theory of Biot was employed, under the assumption of an incompressible solid grain and neglecting the apparent mass density. The loading function was presented by a Fourier series expansion.By using the boundary condition, the governing equations of motion were then solved. The...