Evaluation of the pile interaction at vertical vibrations of foundation

The aim of the work - to research changes in the dynamic stiffness of pile foundations from the distance between the piles during vertical vibrations using experimental data from literature sources and solving wave models describing the vertical vibrations of a thin plate with round cuts. Methods. To verify the reliability of solutions of wave models describing changes in dynamic stiffness during vertical vibrations of pile foundations, it is used data obtained in experiments to determine the eigenfrequencies of 3×3 groups of friction piles with different distances between them. Also the data obtained from forced vertical oscillations of 2×2 groups of friction piles connected by pile-caps at different loads and distances between piles was used. In the processing of available amplitude-frequency curves for determining the dynamic stiffness the inverse problem is solved using the theory of nonlinear oscillations. The correspondence between the measured and predicted data is evaluated, when describing the behavior of the pile-ground system. Results. It is established that the relations that take into account the mutual influence of piles in the group, obtained in the framework of wave models solutions and used for calculating dynamic stiffness in vertical vibrations of pile foundations, allow us to obtain satisfactory results in accuracy. The deviation of the calculation results from the experimental data does not exceed 15%.