Development and Evaluation of Practicable Electrode Configuration for Electro-Osmotic Consolidation as a Support Prefabricated Vertical Drainage (PVD) Using Sandbox Experiment and Numerical Modeling

Stabilizing saturated soft clay presents significant challenges due to its instability and easy compression. Conventional methods, such as Prefabricated Vertical Drains (PVDs), experience diminished efficacy over time. This study evaluates the effectiveness of Electro-Osmotic (EO) consolidation in accelerating soil stabilization within PVD systems by comparing three scenarios: (1) vacuum preloading alone, (2) EO treatment alone, and (3) combined vacuum preloading with EO treatment. Bangkok soft clay, remolded into a slurry to ensure uniformity, was used in sandbox experiments with dimensions of 100 × 100 × 50 cm. PVDs were arranged in a Wenner electrode array, and a three-dimensional numerical model was developed for optimization. Results show that the EO-PVD system outperforms vacuum preloading independently, releasing 2.5 times more water (18,014 cm³ vs. 7,258 cm³) over 20 days, with an increased consolidation rate from 66.3% to 80.5%. Additionally, the microstructural analysis revealed improvements near the electrodes, including increased shear strength and higher Over-consolidation Ratio (OCR). The study demonstrates that combining EO with PVD and vacuum preloading yields superior soil stabilization compared to traditional methods alone, and the developed model with R² exceeding 0.95 effectively guides electrode design for enhanced geotechnical performance.