# Experimental Evaluation of Load Distribution between Piles in Case of Block Failure
## 1 Introduction  
The basic requirements of engineering designs are economy and safety. For this reason, the calculations should be examined in more detail in order to design the piles more safely and economically. In the literature, there are many field measurements, model tests and numerical studies on the investigation of the bearing capacity and settlement behavior of single piles, pile groups and pile raft foundations. Moreover, as it is known, cohesive soils have lower bearing capacity compared to cohesionless soils [1; 2]. For this reason, soil improvement is made in order to provide sufficient bearing strength in clayey soils. Pile foundations are used when soil improvement methods are not economical. However, despite their widespread use, studies on load distribution between piles in pile foundations are limited. Pile load distribution is one of the controversial issues among engineers even today. Some studies on this subject are summarized below.  
[PERSON] [3], who carried out the first studies on this subject, determined in his laboratory experiment on reconstructed clay soil that the pile loads gradually decreased from the center to the corner. Another example of the load difference between the corner and center piles was the Meseuturm Tower. [PERSON] et al. [4] reported that the ratio of corner pile load measured on piles under the Meseuturm Tower building in Frankfurt to the load of the center pile was 3.5. The engineers have designed the length of the corner and center piles differently due to the different load distribution between the piles. In this study, the length of the center piles was 34.9 m, and the length of the corner piles was 26.9 m since the settlement amount must be within acceptable limits. The reason for this design was that the corner piles carried more load in the piled raft foundations at the allowed settlement values. In these conditions, the loads carried by the center piles were smallerthan the corner piles. Thus, the aim was to make the load distribution in the pile group more uniform.  
[PERSON] et al. [5] reported the corner/center pile load ratio (\(\mathrm{q_{cor}}/\mathrm{q_{cen}}\)) as 1.6 in the piles of the Garigliano Bridge that sit on clayeys-silt and sand layers. [PERSON] and [PERSON] [6] found load increases in the corner piles of circular tanks. Likewise, [PERSON] and [PERSON] [7] reported that the corner and center piles of the building in Moscow's Pavshinsk River Valley did not carry an equal pile load. Researchers gave \(\mathrm{q_{cor}}/\mathrm{q_{cen}}\) as 2.4 for the foundation of a building resting on alluvial soil by the river. [PERSON] et al. [8] carried out a loading test on nine piled foundations on a soil consisting of silty-clay and sand layers and reported that the corner pile loads were greater than the center one. [PERSON] and [PERSON] [9] determined that the pile at the corner of the foundation and the center pile carry different loads.  
In addition, there are numerical investigations in the literature that calculate the load distribution of piles [10; 11; 12; 13; 14; 15; 16; 17]. However, although formulas were suggested using the results obtained from these studies, most of these formulas remained at the research level. Therefore, in pile foundation projects, designers have to use finite-element-based programs to determine the load distribution between piles.  
[PERSON] and [PERSON] [18] conducted model experiments and analyzed the load distribution between piles. As a result of this study, they determined that the center piles carried more load than the corner piles when the foundation was loaded from the center. [PERSON] and [PERSON] [19] found that the amount of load carried by the center pile decreased as the number of piles and pile space increased by using FEM.