A Comparative Study of Piled-Raft Foundation by Utilization of Finite Element Techniques: A Review | Original Article
Raft foundation covers the entire area of the structure, transmitting the entire structural load and reduces differential settlements whereas piles are relatively long, slender members that transmit foundation loads through soil strata of low bearing capacity to deeper soil or rock strata having a high bearing capacity. In recent years, a piled-raft foundation which is a composite structure consisting pile and raft has been proved to be an appropriate alternative instead of conventional pile or mat foundations. In this paper, analysis of piled raft foundation has been carried out by using finite element software ANSYS. For understanding the behavior of piled raft foundation, parametric studies has been carried out in medium sand by varying pile diameters and pile lengths in different combinations. It has been found out that Pile diameter has significant influence on the ultimate capacity of piled raft foundation whereas the pile length has not of much significance. It is concluded that an optimum combination of pile diameter of 0.5 m at the center of the raft with 0.4 m at the edges of the raft is giving ultimate load of 4.45 MN with settlement of 26.76 mm which is in acceptable limits. The design of group piles depends on either the group or single pile capacity of piles. In conventional design method of such foundations, the stiffness of the pile cap is barely taken into account. Such design becomes too conservative if the pile cap is in contact with the ground. Because the pile cap contributes in transferring load to the ground and distributing load over the piles. The design method that considers the contribution of the pile cap and interaction between the different elements of group piles is called piled raft foundation. The concept of piled raft foundation leads to economical design.