Numerical analysis on ground improvement of vacuum preloading with prefabricated radiant drain

Abstract

A new technology of vacuum preloading with prefabricated radiant drain (PRD), including prefabricated vertical drain (PVD) and prefabricated horizontal drains (PHD), was proposed in this paper. The validity of numerical model parameter was verified by comparative analysis of deformation development of numerical simulation results and field tests. In addition, two influence factors of PHD spacing and PHD length for vacuum preloading with PRD technique were systematically studied by finite element method. The results show that vacuum preloading with PRD can obviously improve the reinforcement effect of dredged fill ground. Compared with the conventional vacuum preloading, the maximum settlement of vacuum preloading with PRD respectively is increased by 88.94 % and the maximum lateral displacement is 110.4 % at the PHD spacing of 0.5 m. Moreover, reducing the PHD spacing can improve the ground treatment effect. Compared with the PHD spacing of 1.5 m, the maximum settlement respectively is enlarged by 39.93 % and the maximum lateral displacement is increased by 49.4 % for the PHD spacing of 0.5 m. Increasing the PHD length can boost settlement and lateral displacement for the PHD length range of 0.2 m~0.4 m. The settlement and lateral displacement are 38.98 % and 50.3 % higher for the PHD length of 0.4 m than those for a PHD length of 0.2 m.

Recent Developments in the Vacuum Preloading Technique in China

“…The heads of PVDs are directly connected to the horizontal vacuum pipes through a specially designed connector to form the airtight tubing system as shown in Figure 9b. It is found by Lei et al [24] that the effect of vacuum preloading combined with PRD is better than that combined only with PVDs. The PRDs fabricated with horizontal drainage spacing of 0.5 m and installed into the soft clay in a square pattern with the grid of 0.8 × 0.8 m provide the best consolidation effect.…”

“…Another prefabricated radiant drain (PRDs) was proposed by Lei et al [24] to improve the consolidation effect of the dredged clay. As shown in Figure 9, the PRDs were fabricated by horizontally attaching several short PVDs, so-called PHDs, onto a vertically installed PVD.…”