Investigation of the behavior of piled raft foundations under the effect of vertical loads with model experiments on clay soils

There are many model tests, field measurements and numerical studies on the determination of bearing capacity and settlement behavior of single piles, pile groups and piled raft foundations. The data obtained from field measurements were analyzed by using package programs based on finite element method. In the laboratory model experiments, researches were made on soils composed of pure sand or pure clay and these test systems were modeled with finite element method programs. However, pure clay or pure sand soils are scarce in nature and therefore less likely to build structures on these soils. On the basic of this study, a new soil was created similar to the soils in nature to provide widespread land conditions and experiments were conducted on this soil. For this purpose, 50% by weight of clay and 50% by weight of sand material was mixed and a new type of soil was obtained which would be close to the nature. 1.5 times of the liquid limit was mixed with water and placed in the test tanks and consolidated at 100, 200, 300 kPa pressures. Thus, 3 types of homogeneous clay soil with different parameters were formed. The behavior of the pile groups on the obtained soils, the effect of the distance between the piles on the bearing capacity, the presence of block behavior and the effect on the bearing capacity, the raft foundation in contact with the soil, the share of piles and the load from the superstructure were investigated. The effect of changes in soil parameters on the foundation behavior of piled raft was investigated. In addition, in the piled raft foundations, the load to each pile was measured using strain gauges to determine the load distribution mechanism between the piles. Three dimensional geometric models were created under similar boundary conditions with laboratory experiments and analyzes were made using finite element method. Thus, the behavior of piled raft foundations formed on clay soils was investigated using experimental and numerical methods. As a result of this research, it is thought that it will contribute to the deficiencies seen in the literature. As a result of the experiments, it was determined that the increase in the number of piles increases the bearing capacity up to a certain number in both cases where the pile group and the pile group + raft carry the superstructure loads together. It has been determined that the effect of the increase in the number of piles after a certain number on the increase of the carrying capacity decreases and the pile spacing is more important. Similar to the studies in the literature, the piles in the middle region of the piled raft foundation carry more load, while the piles in the edge regions of the piled raft foundation bear less load. If the raft foundation touches the soil, it is observed that there is a significant increase in the bearing capacity.