Study And Application Of The Vacuum Surcharge Preloading In The Highway

In-door tests and in-site tests were performed to study the application of vacuum surcharge preloading in the highway.In the paper, the finite element methods were adopted to calculate the cross-section DK0+400 in order to research the processing of vacuum surcharge preloading, improve the present design methods and enhance the construction level.Though calculating, several conclusions were got as below:1. The calculation results from three models: elastic-plasticity model, visc-plasticity model and visc-plasticity rupture model were compared with the experimental results, which show that the result from the visc-plasticity rupture model can match the experimental results well. Obviously, the visc-plasticity rupture model can simulate the vacuum surcharge preloading accurately.2. By comparison of horizontal displacement and depth, deformation mainly occurs in consolidation area. Therefore, it is the key point to shorten the dissipation of vacuum.In this paper, conclusions can be got as below:1. Vacuum preloading methods enhance the effective stress by reducing the pore stress, while surcharge preloading methods enhance the effective stress by enhancing the total stress in the soils. Therefore, soft subsoil was strengthened more effective through vacuum surcharge preloading than by vacuum preloading or by surcharge preloading.2. Vacuum surcharge preloading methods induced consolidation stress, but no shear stress; therefore, vacuum can be applied at a time with the subsoil not failing.3. Vacuum surcharge preloading methods can be more easily simulated by mathematic models when used to strengthen the soft subsoil.