ABSTRACT: A power plant project in South Vietnam was to be constructed on 16-30m depth very soft muddy clay layer. The project covered an area of 25.3 hectare. The very soft clay layer had a natural water content of around 58%, initial void ratio 1.594, and compression index 0.615. Vacuum preloading with an average PVD length of 26m and vacuum pressure of more than 80 kPa, was employed to improve the soft soil. The vacuum degree, surface and subsoil settlement, pore water pressure and lateral displacement were carefully monitored during the preloading period. After the vacuum preloading period of 117 – 150 days, ground surface settlement of 1.254-1.655m correspond to a degree of consolidation over 90% was achieved. The maximum lateral displacement was176mm in the direction towards the improved area. The after treatment Vane Shear Test yields undrained shear strength, Su, is 40 ~ 70 kPa.
Download full paper: 2012-Dec-Hatti-Vacuum Preloading Soil Improvement for a Vietnam Power Plant Project