Influence of Bending of Plastic Vertical Drain on Consolidation via Vacuum Preloading

Abstract

The soft ground improvement employing vacuum preloading is widely used in Tianjin. In the application of vacuum preloading, the bending of plastic vertical drains (PVDs) often occurs accompanying the large settlement of the soft ground or the significant shear strain at the ground surface. In order to investigate the influence of bending of PVDs on the ground consolidation, three different bending shapes of PVDs are assumed and a series soil-water coupled finite element analyses are carried out. It is found that: 1) the macro-element method is available to take the bending effect of PVDs into consideration; 2) the bending at the bottom of PVDs has much impact on the consolidation of ground even though the hydraulic gradient at the bottom is much smaller than that at the top; 3) Due to the bending of PVDs at the bottom the drainage capacity is much influenced and the volumetric compression only occurs at the first few layers of the ground.