PERFORMANCE OPTIMIZATION OF COMPOSITE PILED RAFT FOUNDATION THROUGH ENCASEMENT OF SHORT GRANULAR PILES

Soft clay soils present significant challenges to geotechnical engineering due to their high compressibility, low shear strength, and excessive settlement underloading. To overcome these challenges, this study examines the effectiveness of geosynthetic encasement of short granular piles within composite piled raft foundations (CPRF) in enhancing the performance of the foundation system studied. Accordingly, series of three-dimensional finite element analyses are performed using PLAXIS 3D to evaluate the influence of geosynthetic stiffness and the encasement length, for two granular pile diameters (0.4 m and 0.5 m), on the performance of uniformly loaded CPRF in drained conditions. The study focuses on the lateral deformation of the granular piles, the settlement performance of the CPRF, and the distribution of loads among long rigid piles, short granular piles, and the surrounding subsoil, as well as the axial forces mobilized in both pile types. The results reveal that geosynthetic encasement significantly improves the efficiency of short granular piles by reducing their lateral deformation, improving axial load resistance, and facilitating better stress transfer to the surrounding soil, which contributes to reduced overall settlement of CPRF and a significant improvement in the performance of the CPRF system. The study also presents several recommendations pertaining to the future scope.