Analysis of Physical Modeling of Cast-In-Situ Concrete Piled Raft

Abstract

Nowadays, there is competition for constructing high rise buildings, and the reason may be due to decreasing availability of land due rapid industrialization and urbanization. This has increased heavy load, complicated stress conditions, and having limitation of bearing capacity of soil. This results in settlement of high rise buildings. This leads to use of piled raft foundation. But the load-bearing capacity of piles is not considered, they are used as settlement reducers only, and load is carried by raft only. In another design method, axial capacity of the piles to carry the structural load and bearing capacity of raft is neglected. In both the design approach, piled raft foundation becomes uneconomical. Now research is going on for considering the load-bearing capacity of both pile and raft and developing detail analysis. In a pile raft foundation, pile-soil-raft interaction is complicated. Although several numerical studies have been carried out to analyze the behaviors of piled raft foundations, very few experimental studies are reported in the literature. The available laboratory studies mainly focus on piles made with steel or aluminum. The present study aims to study the behaviors of piled raft foundation, in the laboratory using physical model. The physical model is made up of cast-in-place reinforced concrete piles, and reinforced concrete raft are used for the tests. The test is conducted on single pile, pile group, un-piled raft, free-standing pile group, and piled raft foundation. We examine the effects of numbers of piles, the interaction between different components of foundation, and load-sharing ratio of pile and raft. The results indicate that the ultimate bearing capacity of the pile raft foundation is considerably higher than that of free-standing pile group with same number of piles.