Effect of Battered Piles on the Response of Piled Raft and Pile Group Foundations A Numerical Study

Abstract

The piled raft (PR) foundation system combines a shallow raft with deep piles, mobilising both components through complex raft–pile–soil interactions. Due to its effectiveness under vertical and lateral loads, it is widely used to support tall, heavily loaded structures. However, the complexity of the system often leads to reliance on simplified design methods. This study uses numerical simulations in FLAC3D to investigate the effect of pile battering on the behaviour of PR and pile group (PG) foundations in drained sandy soils. Unlike previous research combining vertical and battered piles, only battered piles are adopted here to isolate their influence under combined loading. A batter angle of 10° is selected to avoid excessive bending moments. Results indicate that battered piles improve lateral resistance in PR foundations by up to 66%, though vertical capacity is slightly reduced (by 14%) due to axial–bending interaction. Under combined loading, vertical piles outperform battered ones in overall resistance gain (55.7% vs. 38.8%), mainly due to improved soil confinement. Batter piles also play a key role in reducing tilt and enhancing foundation stability. This study offers practical insights for designing foundations exposed to strong lateral forces, such as in offshore structures and wind turbines.