Study On Dynamic Responses Of Highway Subgrade And Cumulative Deformation Of Underlying Soft Subsoil Due To Traffic Loads

Researching the dynamic response of Highway subgrade, predicting the cumulative deformation of the soft subsoil due to traffic loads can be very instructive to practical project design. Based on fundamental theories for elastic and Biot saturated media, a double-layered ground model was established as a reinforced Highway soft subgrade and a study of its dynamic stress and excessive pore pressure due to traffic load was performed. After that, an empirical cumulative deformation model was proposed and the cumulative deformation of the soft subsoil under cyclic traffic loads was calculated. The main contents are as follows:1. A reinforced Highway soft subgrade model under traffic load was established, with elastic medium modeling overlying reinforced layer and Biot saturated medium modeling underlying soft subsoil. Based on general solutions to motion equations for elastic and Biot saturated media, coupled with subgrade’s boundary conditions, the analytical results of dynamic response in the double-layered subgrade under traffic load was acquired by matrix operation;2. By assigning the subgrade practical parameters, the numerical results of vertical dynamic stress and excessive pore pressure were obtained, and their distributions in the subgrade were analyzed, additionally, the influences of load speed and some model parameters were studied;3. By use of an empirical cumulative strain model for soft soil, coupled with the dynamic deviatoric stress of saturated subsoil, this article made a study on cumulative deformation of soft subsoil in Highway subgrade due to traffic loads. The calculated results of cumulative deformation were compared with the measured values, and a study on influences of parameters like traffic load speed was performed.Considering the difference of mechanical properties between reinforced layer and soft subsoil after subgrade reinforcement, this article established the subgrade model with both elastic medium and Biot saturated medium; Unlike most calculation methods based on empirical models, in this article. the dynamic deviatoric stress was determined through dynamic response research, which considers load speed’s influence.