A Modified Substructure Method for Complex 3D Finite Element Analysis of PVDs with Vacuum Preloading

The complex three-dimensional (3D) finite element analysis of prefabricated vertical drains (PVDs) still has some problems, such as intricate modeling and expensive computational efforts. This paper aims to propose a modeling method to solve these problems. The traditional drainage substructural method without modification is relatively low in computational accuracy when used for 3D finite element analysis of PVDs. This paper proposes a modified substructure method suitable for 3D finite element analysis of PVDs under vacuum pressure. This method corrects the horizontal permeability coefficient of the soil in the smeared area and proposes a specific correction formula. The modified substructure method is verified from the unit cell 3D finite element model (FEM) and the multi-well 3D FEM. The results of the unit cell 3D FEM are compared with the axisymmetric analytical solution. The settlement results of multi-drain 3D FEM are validated with the field data of Tianjin Port case. The modified substructure with rectangular equipotential line can reduce the number of nodes of 3D FEM to 1/3 − 2/3 under relatively high calculation accuracy; the modeling process is relatively simple; reflect the actual situation of PVDs better. A new modeling choice is presented to conduct the complex 3D finite element analysis of PVDs.