Performance Evaluation of PVD-Reinforced Soft Soil with Surcharge and Vacuum Preloading

Preloading method has been a widely used alternative to improve soft soil in coastal areas in China. In this paper, a field test of PVD-reinforced soft soil with surcharge preloading and vacuum preloading was introduced. Based on the field test, three-dimensional finite-element analyses were conducted to evaluate the performance of reinforced soft soil. The subsoils were simulated as linearly elastic–perfectly plastic materials with Mohr–Coulomb failure criteria. The PVDs were modeled individually as solid elements with the cross section of real PVD. The computed settlements, layered settlements, lateral displacements and excess pore water pressure were compared with the field data. The results show that the differential settlement on the ground can be minimized in the vacuum preloading. However, the environmental influence area of vacuum preloading was greater than that of surcharge preloading outside the reinforced area. The influence depth of vacuum preloading under PVD base was time dependent. And the cut-off wall had a significant effect on mitigating vacuum loss at the boundary.