Experimental Investigation of piled raft foundation on Cohesionless Soil

Abstract

The combination of piles and raft foundation is known as piled raft foundation. Piled raft foundations have proven to be more cost-effective and capable of meeting safe bearing capacity and serviceability norms in the case of high-rise buildings on cohesionless soil. The behavior of a stacked raft foundation is influenced by the piles, raft, and soil. The stacked raft system’s bearing capacity is improved and settlement is minimized when the ground beneath the raft foundation bears the burden of supporting the applied loads. The piled raft foundation minimizes total settlement and improves bearing capacity more than the raft foundation. When isolated footings cover more than 70% of the building area under a superstructure, raft foundations are used, and the present study focuses on the vertical load bearing capability of piled raft foundation systems on cohesionless soil for concentric loading. The use of strategically positioned piles increases the load capacity of the raft while reducing differential settlement. The present study sheds some light on the use of piles as raft foundation settlement reducers, as well as the behavior of a piled raft in sand. A series of small-scale model experiments were carried out. The present investigation studies by varying pile length and alignment on the ultimate load of piled raft foundation. The results indicate that for a 10mm raft thickness, installing 4 piles, 6 piles, and 9 piles by varying L/D ratios of 5,10,15,20 carries significant load. In this present work for a 50mm length of pile, and the value of load improvement ratio increases by 36 percent, 60 percent, and 68 percent, respectively, when compared to plain raft.