A State-of-the-Art Review of Piled Raft Foundations Focusing on Behavioral Mechanisms and Emerging Research Needs

Piled raft foundations (PRF) provide an effective solution for supporting heavily loaded structures where shallow foundations alone cannot satisfy settlement or bearing requirements. Over the past several decades, rapid developments in numerical modelling, experimental testing, and field monitoring have significantly advanced the understanding of PRF behaviour. However, the design of these systems remains challenging because of complex soil-pileraft interactions, variable loading conditions, and differing performance between connected and disconnected configurations. This review is motivated by the need to consolidate dispersed research findings and to identify the critical gaps that continue to limit reliable and economical PRF design. The paper systematically reviews the historical evolution, design philosophies, load-transfer mechanisms, settlement behaviour, and interaction effects governing PRF performance across various soil types. Key themes include behaviour of connected piled rafts (CPR) under axial, horizontal, and eccentric loads, performance of disconnected piled rafts (DPR) with granular cushion layers, influence of pile number, spacing, length, raft stiffness, and soil density on load sharing; and recent experimental and centrifuge studies validating numerical modelling trends. Despite extensive progress, significant gaps remain in understanding CPR-DPR comparative behaviour, performance of vertical versus battered piles, and the role of geosynthetic layers in enhancing load distribution and reducing settlement. The review concludes that PRF systems can substantially reduce differential settlement, improve load-carrying efficiency, and lower construction costs when optimally designed. The implications of this synthesis highlight the need for integrated design approaches, advanced modelling techniques, and targeted experimental research to improve the reliability and resilience of piled raft foundations in modern geotechnical engineering.