The working mechanism of cushion in rigid pile composite ground is analyzed conceptually.Based on that

loading tests were performed on rigid-pile composite ground where pile has very large vertical stiffness to investigate the behavior of cushion of rigid-pile composite ground under vertical load.Gravel cushion with different thicknesses is laid beneath loading plate

while pile head is thus separated from loading plate by the gravel cushion.Pile head was embedded in the cushion for a certain length in one of the tests.Test results show that the bearing capacity of pile even with 100mm thick cushion can hardly be mobilized.The embedment of pile head into cushion can increase the load carried by the pile head;in the meantime reduce the penetration of pile head up into the cushion.