Model tests on stress and deformation properties of composite foundation with controllable rigid piles and drainage bodies

In a composite foundation, the deformations of piles and soils are affected by many factors. The cushion is difficult to coordinate and match the differential settlement between all piles and soils. Therefore the piles often carry the excessive loads and are destroyed, or the piles bear too small loads and are wasted. A new composite foundation composed of controllable rigid piles and drainage bodies is proposed. The differential settlement between piles and soils is coordinated by the grouting device at the top of piles in the composite foundation, rigid piles hardly carry the upper loads before grouting, and the foundation soils are fully consolidated and their bearing capacity is improved. After grouting, the rigid piles begin to support the loads, and the piles and soils work together to share the loads and to control settlement. The stress and deformation properties of the composite foundation are studied through indoor model tests. The results show that the settlement of the new composite foundation mainly increases before grouting and is effectively controlled after grouting. Moreover, the new composite foundation can effectively reduce the differential settlement. The load pressure shared by the cover plate on piles is less than that shared by the soils between piles before grouting, and the pressure shared by the cover plate increases rapidly after grouting, while that by the soils between piles decreases correspondingly. The bearing capacity of rigid piles can be controlled by grouting.