Model Vibration Tests on Piled Raft and Pile Group Foundations in Dry Sand

In this research, the authors carried out vibration load tests on piled raft and pile group models to investigate dynamic behaviours of the foundations. Foundation models consisting of 6 piles, with or without batter piles, were used in the experiments. They were pile rafts (6PR and 6BPR) if the raft was in contact with ground surface, while they were pile groups (6PG and 6BPG) if the raft was not in contact with ground surface. To create dynamic load acting on the foundation, a vibro-hammer, placed on the raft, was used. The vibro-hammer can provide vibration load (active shaking) mainly in the vertical direction (called vertical loading) or in the vertical and horizontal directions simultaneously (called combination loading) by rotating two discs of eccentric mass synchronously in opposite directions or the same direction, respectively. Active shaking tests were conducted on 4 types of pile foundation models (6PR, 6BPR, 6PG and 6BPG) in a consistent dry sand ground. The experimental results indicate that the piled rafts are more effective foundation type to decrease settlement and inclination under dynamic loading than the pile groups.