Numerical Analysis of a Geosynthetic-Encased Granular Pile Anchor Subjected to Uplift Load in Cohesionless Soil

The study investigated the failure mechanisms of granular pile anchor (GPA) and geosynthetic-encased granular pile anchor (GGPA) in cohesionless soil using three-dimensional (3D) finite element (FE) simulations. The analyses evaluated the effects of embedment ratio (L/D), pile diameter (D), pile length (L), and relative density (RD) of the soil on uplift load capacity (ULC) and the load-displacement response. The results showed that GGPA performed better than GPA, achieving a ULC approximately 1.5–2 times higher at L/D ratios of 7.5 or greater. However, GGPA with an L/D ratio of 5 or less exhibited lesser performance than GPA due to slippage failure. An increase in the RD of the soil from 40 to 80% enhanced the ULC by 15–20% for GPA and 17–30% for GGPA. Furthermore, an increase in the D from 20 to 50 cm and the L/D ratio from 5 to 15 resulted in a ULC improvement by a factor of 4.5 to 7.5 for both systems, with GGPA showing a higher percentage increase. Variations in the soil’s modulus of elasticity significantly influenced performance, as soils with a higher modulus yielded a 30–50% increase in ULC. The results offered key insights for optimizing foundation design.