Vacuum Preloading Method In Wenzhou, In The Soft Soil Reinforcement And Environmental Effects Research

Vacuum Preloading has been widely used in china as an economical and fast technology to improve the soft foundation.Recently,the application of the vacuurn preloading technology is more and more gradually.On the basis of the summary of the mechanism of vacuum preloading and analysis of the character of the soft soil in Wen Zhou city, it was studied the characteristics and zone of influence in soft foundation reinforcement based on the practice of the project in Wen Zhou sewage farm and the field test data measured, then it was suggested some improvements of construction technique.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 during the process of vacuum preloading reinforcing the soft soil . The main contents presented in this thesis can be summarized as follow:(1).The machanism of the vacuum preloading reinforcing the soft soil was explained by analysing the concretion mechanism. And the advantage of convenience, hign efficiency and lower cost were unambiguous by analysing vacuum preloading and vacuum combined with surcharge preloading.(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.(3)Based on the project and according to the technics flow of construction this paper suggested some improvements of construction technique about installing plastic drainage board , ubiquity of the sand layer and the way of setting the sand layer. And the influence should be considered adequately before using vacuum preloading to improve the soft foundation.