Bearing Behavior of Cast-in-Place Expansive Concrete Pile in Coral Sand Under Vertical Loading

Abstract

The low side friction of piles in coral sand results in the low bearing capacity of foundations. In this paper, expansive concrete pile is utilized to improve the bearing capacity of pile foundations in coral sand. Both model tests and numerical simulation are performed to reveal the bearing mechanism of expansive concrete pile in coral sand. Results showed that the lateral earth pressure near pile increases obviously and the side friction of piles is improved, after adding expansion agent to the concrete. The horizontal linear expansion is 1.11% and the bearing capacity increased 41% for the pile, when 25% expansion agent is added. Results in finite element numerical simulation also show that ultimate bearing capacity increases with the increase of the linear expansion ratio. Besides, the area for obvious increase in side friction is below the surface of soil about three times the pile diameter, and the expansion leads to a high side friction sharing of the pile. Therefore, the cast-in-place expansive concrete pile is effective in improving the bearing capacity of piles in coral sand.