Numerical Evaluation of Behavior of Tapered Piled Raft in Loose Sand

Tapered piles, with a larger diameter at the top than at the bottom, provide higher shaft resistance than conventional cylindrical piles and may offer a more economical alternative. Adding piles to a raft foundation improves its bearing capacity and reduces settlement. While tapered piles have been investigated for decades, limited research has focused on tapered piled raft systems. This study evaluates the behavior of piled rafts incorporating tapered and cylindrical piles of varying lengths and configurations in sandy soil. The model includes a raft measuring 15 × 15 × 0.7 meters, and piles with an average diameter of 1 meter. The taper angle of 1.20 degrees results in top diameters of 1.25, 1.376, and 1.502 meters and bottom diameters of 0.75, 0.624, and 0.498 meters for pile lengths of 12, 18, and 24 meters, respectively. A 3D finite element model was developed using PLAXIS 3D. Multiple simulations were performed with various pile types and arrangements. The model was validated against three experimental studies, confirming its reliability. Results show that tapered piles offer greater shaft resistance than cylindrical piles. Central piles carry less load compared to edge and corner piles. Increasing the number of piles reduces differential settlement. Additionally, tapered piled rafts demonstrated lower differential settlement than cylindrical piled rafts, highlighting their effectiveness in enhancing overall performance.