Experimental and Numerical Investigation for Vertical Stress Increments of Model Piled Raft Foundation in Sandy Soil

Abstract

Piled raft foundations have become a prominent foundation system in recent years as they combine bearing capacities of piles and raft. For this reason, comprehensive analytical, numerical and experimental studies have been carried out for reliable and economic design of piled raft foundations. In this study, vertical stress increments were mainly investigated experimentally and numerically. In the experimental study, model composite (steel and concrete) piles with a diameter of 20 mm and lengths of 200 and 300 mm were used. The raft was made of steel plate with plan dimensions of 160 × 160 mm and a thickness of 6 mm. The pressure gauges were placed at 2.5D, 5D and 7.5D intervals axially below center of model piled raft in the sand. The tests were carried out at different relative densities with the model piled raft. After model tests, numerical analyses were carried out with the FEM-based software ABAQUS, and the results were compared with the experimental results. From the tests results, it is determined that the piled raft foundations transfer loads to the deep layers with the help of piles, and the vertical stress increment reduces downward from the end of the piles. However, it is seen that the increase in relative density decreases the vertical stress increments in sand for same load. Some design parameters are suggested for use in foundation engineering applications.