Numerical Simulation of Geogrid Encased Stone Column beneath the Oil Storage Tank Using Plaxis-3D

Geosynthetic Encased Stone Columns (GESCs) represent a significant advancement over traditional stone columns (OSCs), particularly in improving the performance of ground support beneath circular oil storage tanks. Using PLAXIS 3D simulations, it was observed that GESCs provide enhanced settlement control and lateral restraint due to the increased lateral confinement offered by the geosynthetic encasement. The study varied key design parameters including column length-todiameter ratio (L/D), spacing ratio (S/D), area replacement ratio, and encasement length. Results showed that longer columns, especially when paired with high geogrid stiffness, significantly reduced both long-term settlements and lateral spreading of the ground. Among the spacing ratios tested, reducing S/D from 4 to 2 led to a 45.9% reduction in settlement for short columns (L/D = 2), a 63.5% reduction for medium (L/D = 4), and up to 82.5% for the longest columns (L/D = 6), emphasizing the stronger effect of spacing with increased column length. Similarly, increasing area replacement ratio improved overall ground stability and load distribution. Regarding encasement length, extending it from 2D to 8D resulted in a 32.1% reduction in settlement, with the most substantial improvement noted between 2D and 4D; further increases beyond 4D provided only minor benefits. Therefore, a 4D encasement is considered optimal, providing effective settlement control while remaining cost-effective. Settlement profiles across the tank’s radial distance confirmed GESCs’ superior performance over OSCs in reducing ground movement. Analyzing the effect of stone column by different area replacement ratios along with improvement factor and stress concentration ratio. Overall, GESCs designed with optimal parameters of column length, spacing, area ratio, and encasement length offer increased efficiency, stability, and cost savings for oil tank foundations on soft clay.