A permeable pipe pile is proposed to accelerate the dissipation of excess pore-water pressure through drainage holes around the pile circumference into the pile’s cavity. This investigation generalizes the permeable pile–soil interface as an impeded boundary, based on which a mathematical model for soil consolidation around the permeable pile is derived. Subsequently, the influence of opening pattern, drainage hole-to-pipe pile radius ratio, and opening ratio on the consolidation efficiency is numerically investigated. A total of 240 numerical cases with different drainage hole-to-pipe pile radius ratios, opening ratios, and hydraulic conductivity ratios are calculated to determine the permeable pile–soil interface parameter using back-analysis, and an approximate expression for interface parameter is obtained. Comparing against experimentally measured excess pore-water pressure dissipation, the proposed technique with impeded drainage boundary can provide good evaluations for drainage characteristics at the permeable pile–soil interface and consolidation behavior of the surrounding soil. It is found that the spatial distribution pattern of drainage holes has negligible influence on the consolidation efficiency. Increasing the opening ratio (with constant opening size) or reducing the drainage hole-to-pipe pile radius ratio (with constant opening ratio) can both accelerate the consolidation efficiency.

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.