# Numerical Investigation of the Pile-Soil Interaction Problem under Dynamic Loads
## 5 Conclusions  
In this study, the behavior of piles under dynamic loads was investigated under kinematic conditions. For this purpose, the results of an experimental study in the literature were verified with a finite element program, and the effects of parameters such as soil conditions, groundwater level, pile stiffness, and earthquake magnitude were investigated. The results obtained are summarized below. Figure 16: Pile cap displacement–acceleration curves. Figure 17: Maximum moment–acceleration curves. * The results obtained from the centrifuge experiment by [PERSON] et al. [13] were confirmed with numerical analysis results obtained using a finite element program in this study. * In the kinematic interaction analyses, with the increase in the weak soil layer thickness in layered soil conditions, although there was no significant increase in the displacement values at first, significant increases were observed in the pile cap displacement at the depth where the clay layer thickness reached approximately 75% of the total pile length. No significant increase in displacements was observed as the clay layer thickness reached larger values. This was due to the fact that the pile behaves more flexible under kinematic conditions as the number of sockets in the dense sand decreased. * In the analyses of the investigation of the effect of the groundwater level, considering the stratified situation, it was seen that the displacement increased with the increase in the depth of the groundwater level, and there was no significant change in displacement after the water level reached -6 m. This situation was caused by the groundwater level approaching the underlying sand layer, and the effect of the groundwater level remaining in the sand on deformation decreased. * In the only-clay soil, it was observed that as the groundwater level increased, the deformation first decreased, and then the deformation increased. The decrease in the groundwater level caused the upper layer to behave more rigidly and the deformation to decrease up to a certain level. As the water level decreased below the bottom elevation of the pile, the pile behaved flexibly, and its deformation increased. * In the analyses examining the effect of pile stiffness, it was observed that deformation decreased as the elasticity modulus increased in the layered case, and there was no change in deformation after the elasticity modulus reached the 70 GPa value used in the experiments. For the only-clay soil, it was seen that the deformation increased with the increase in the elasticity modulus, and there was no change in deformation after reaching the value of 70 GPa. In this case, it is understood that the elasticity modulus was effective as it approached the soil elasticity modulus, and the effect decreased after a certain stiffness. * In the analysis examining the earthquake magnitude effect, it was seen that displacements and moments increased linearly with the increase in earthquake acceleration. The results obtained show that the earthquake magnitude is the most important parameter affecting the results. * When the results obtained are evaluated from a practical engineering perspective, it is understood that the piles, which are adequate for design under static loads, are exposed to significant bending moments under dynamic loads. Therefore, it is of great importance to take dynamic loads into consideration in the design stage. In addition, under dynamic loads in weak soil conditions, the largest displacement occurs in the pile head, while the highest bending moment occurs in the transition between soil layers. Additional precautions should be taken by increasing the steel reinforcement ratios in the pile foundation connection areas and in the transition between soil layers. * Earthquake forces are one of the most important factors that directly affect the design of pile systems. Therefore, using accurate earthquake data is important for design. Selecting earthquake data by taking local soil conditions into consideration will make the design more realistic.