Analysis And Study On The Observed Data Of Reinforcing Soft Soils Foundation By Vacuum Preloading Method

Soft soils show low strength, high compressibility and low osmotic permeability, so soft soils must be reinforced before people build expressway, port and dock etc on them. Vacuum preloading method is effective to improve the soft soils foundation. The settlement and stability problems are well solved by this method and the time limit for a project is shortened. However, there are still many problems on the research of improvement mechanism. These problems have restricted its wider application and development.By means of theoretical analysis and field monitoring, the improvement mechanism of vacuum preloading method is analyzed. The variation rule of surface settlement and horizontal displacement, groundwater level, pore water pressure and vane-shear strength of foundation is studied. The main contents presented in this thesis can be summarized as follow:1. Based on the present research results, the improvement mechanism and calculation means of vacuum preloading method and conventional surcharge preloading method are discussed, and then their characteristic and difference are compared. Some viewpoints are proposed on that people calculate settlement in vacuum preloading method by means which are fit for surcharge preloading method.2. Based on the field monitoring data of project, the variation rule of surface settlement, lamination settlement, pore water pressure, groundwater level, and vane-shear strength of foundation in different depth of the foundation during vacuum preloading is studied in this paper. The improvement effect is discussed, and suggest on how to get the real groundwater level data in monitor measure is proposed.