Parametric Study on the Performance of Disconnected Piled Raft System on Soft Soil Under Vertical Load
摘要
Piled raft foundation is generally preferred in soft soil for high rise buildings. In connected pile raft (CPR) foundation, the highest axial load occurs at the pile head, causing substantial bending moments in the pile, leading to structural failures when exposed to lateral or seismic forces. An alternative approach to eliminate such failure was to disconnect the piles from the raft using a layer of granular material as cushion. Thus, the objective of the present study is to evaluate the effectiveness of connected and disconnected piled raft foundations on soft soil subjected to static vertical loads under varying geometrical parameters of the system. The parametric study involved the variation of cushion layer thickness, pile stiffness, pile length, and pile diameter. The performance of a disconnected piled raft (DPR) system, was evaluated in terms of raft settlement, load-settlement response, axial force distribution and skin friction variation along the pile, load sharing ratio, etc. The thickness of the cushion layer significantly influenced the load-carrying behaviour of piles, with a thickness of 1 m found to be effective. As the pile length increased, more pile capacity was mobilized at greater depths due to enhancement in subsoil stiffness. With increase in pile stiffness, the settlement decreased due to higher load sharing tendency by the stiffer piles. The varying pile lengths for middle, edge and corner piles were noticed to be efficient in reducing the average as well as differential settlement of the disconnected piled raft (DPR) system. Similarly, the larger diameter piles tend to take more load resulting in efficient utilization of pile capacity with reduced settlement response. Negative skin friction was observed to be dynamically varying during consolidation which significantly changed the axial load along the length of piles requiring in-depth exploration about the efficiency of disconnected piled-raft (DPR) system.