Discussion on Reinforcement Mechanism and Construction Technology of Pressurized Vacuum Preloading

Based on the basic theory of vacuum preloading, this paper proposes an good effect of pressurized vacuum preloading in which the high pressure gas results in tiny cracks between the air pressurized pipe and band drain. Therefore additional drainage paths are introduced to improve the permeability of soil and accelerate soil consolidation. But field tests show that the advantages of pressurized vacuum preloading are not obvious compared with conventional vacuum preloading, and the soil settlement, soil properties and vane shear strength are slightly lower than those by conventional vacuum preloading. The vacuum pressure transmission is analysed in the air pressurized pipe and band drain as well as the dissipation of pore water pressure in the soil during the pressurization process, it is concluded that the unsatisfactory reinforcement effect is mainly due to the sealing problem between the top of the air pressurized pipe and the sand cushion, and the overlap problem between the booster pipe and band drain