Model test on vertical bearing capacity of X-section concrete pile raft foundation in silica sand

To reveal the bearing capacity of the X-section concrete piles pile raft foundation in silica sand, a series of vertical load tests are carried out. The X-section concrete piles are compared with circular section pile with the same section area. The load-settlement curves, axial force and skin friction, strain on concave and convex edge of the pile, pile-sand stress ratio, distributions of side and tip resistance are presented. The results show that bearing capacity of the X section concrete pile raft foundation is much larger than that of the circular pile raft foundation. Besides, compared with the circular pile, the peak axial force of X-section piles under raft is deeper and smaller while the neutral point of X-section concrete pile is deeper. Moreover, the strain on the concave edge is much larger than that on the convex edge of the pile, and the convex edge has more potential in bearing capacity as the vertical load increases. The X-section pile has higher pile-sand stress ratios and load-sharing between side resistance and tip resistance. Above all, the X-section concrete pile can significantly increase the bearing capacity of pile-raft foundations in silica sand.