Semi-Analytical Solution for Consolidation of Ground with Partially Penetrating PVDs under the Free-Strain Condition

Free-strain solutions for consolidation of ground with partially penetrating prefabricated vertical drains (PVDs) cannot be solved analytically using the integral transform method due to the irregularity of the solving domain and the complexity of boundary conditions. In view of this, the solving domain is simplified based on the smear zone equivalent method, which can be immediately solved using integral transform, boundary transform, and local discretization methods with different vertical boundary conditions. The effectiveness of the simplified model and the proposed semi-analytical solution is then evaluated against calculations using the finite-element method. Once the proposed approach is calibrated successfully, a parametric investigation is carried out to assess how the consolidation behavior of the PVD-improved ground is influenced by the permeability coefficient, radius, and penetrating depth of PVD. Results show that a larger permeability coefficient/radius of PVD can decrease the well resistance, resulting in a higher radial average degree of consolidation in the ground at all depths. However, the increase of penetrating depth of PVD not only provides more drainage channels, but also increases the well resistance of PVD, which decreases the radial average degree of consolidation in the improved layer locally.