Liu Run

Study on effect of vacuum preloading method improving hydraulic filled soft clay

Vacuum preloading is an effective method to improve the soft soil foundation. After vacuum preloading, the bearing capacity of the ground can reach to 80 kPa, which meets the design requirement for most of goods yards, warehouse, low-rise industrial and civil constructions. Vacuum preloading method is widely used to improve hydraulic filled soft clay in Tianjin Port. During vacuum preloading, the ground settlement along the depth, the lateral deformation of the area boundary and the pore water pressure in the soil are all necessary reference parameters to control construction procedure. Carrying out vane tests before and after vacuum preloading is another important measure to evaluate the improvement effect of vacuum preloading. Based on the practical experience of Tianjin Port, the monitoring measures and reference parameters which are generally used in the vacuum preloading are concluded. The soil foundation deformation and the effective stress increase during the vacuum preloading are simulated by numerical methodology.

An FE analysis of reinforced subgrade under automobile loading

An FE analysis procedure was presented to predict the behavior of soil-geogrid interaction under automobile loading. The dynamic interactions between the transverse bars, the longitudinal ribs and the soil were simulated by a system consisting of nonlinear springs, dashpots and masses, to study the deformation properties of the reinforced soil. The equivalent stiffness and damping ratios could be determined with the shaking table. The dynamic responses of a reinforce subgrade were analyzed with the 3D finite element approach. This approach is programmed and applied to analyze the soil-geogrid interaction under dynamic loading. The comparative analysis of the response of the reinforced subgrade and that of the subgrade without reinforcement shows that the geogrid placed at the bottom of the base layer may effectively reduce the accumulative plastic deformation due to the cyclic automobile loading.