Optimum geometric design in spacing and depth for prefabricated vertical drains (PVDs) to accelerate the consolidation rate with validation by finite element modelling (PLAXIS 3D)

One of the common practices in the field of geotechnical engineering is the use of prefabricated vertical drains (PVDs) for ground improvement work. PVDs provides shorter drainage paths to hasten the consolidation process. The performance of the PVDs depend on the spacing, length and characteristics of the PVDs, and the condition of the surrounding subsoil. Three case studies were carried out for the validation process by comparing the actual results from PLAXIS 3D with manual spreadsheet predictions. For this research, PVDs with four 4 different spacings and lengths were constructed at the sites to obtain an optimum geometric design. Based on the analytical calculations, simulation predictions and actual results from the sites, the PVDs installed with a triangular pattern and a spacing of 1.2 m and depth of 36 m achieved the highest settlement reading and consolidation rate in 6 months, with an accuracy of 86.5% for the validation process.