Performance Evaluation of Disconnected Piled raft foundation Incorporated with Polystyrene Cushion and Hybrid Geogrid-Geotextile Base

Foundation systems are critical to ensure structural stability, particularly in challenging geotechnical conditions. This study introduces a disconnected piled raft (DPR) foundation system incorporating a polystyrene cushion platform reinforced with geogrid and geotextile layers to enhance load distribution, minimize differential settlement, and improve overall performance. The proposed DPR system addresses the limitations of conventional piled raft foundations by reducing the rigidity at the raft-pile interface and promoting more uniform load transfer. The research methodology involved numerical modelling using PLAXIS-3D and laboratory experiments to evaluate the performance of the DPR system. Material properties of the polystyrene cushion, geogrid, and geotextile were characterized, and boundary conditions were defined to simulate realistic loading scenarios. Comparative analysis with traditional vertical piled raft (VPR) and battered piled raft (BPR) systems was conducted under varying load conditions. Results demonstrated that the DPR system supported a maximum load of 18.2 kN with a settlement of 10 mm, surpassing the performance of connected systems. The settlement efficiency ratio of approximately 32% was significantly higher than the (10-17) % efficiency observed in conventional systems. Additionally, the DPR system exhibited optimized stiffness, achieving equivalent stiffness at 1 kN compared to 17 kN for connected systems, and reduced unit skin friction to -2 kPa, ensuring effective load diffusion. The study concludes that the DPR foundation system offers an innovative solution for modern foundation engineering, providing superior load-bearing capacity, enhanced settlement control, and improved structural efficiency through the integration of advanced geosynthetic materials.