Horizontal Stiffness and Damping of Piles in Inhomogeneous Soil

Xenia Karatzia, George Mylonakis*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

28 Citations (Scopus)
1373 Downloads (Pure)


A practically oriented analytical procedure for determining the dynamic stiffness and damping (impedance coefficients) of a laterally loaded pile in soil exhibiting different types of inhomogeneity with depth, is presented. To this end, an energy method based on the Winkler model of soil reaction in conjunction with pertinent shape functions for the deflected shape of the pile are employed. A new elastodynamic model for the wave field around a pile is also introduced. The method is self-standing and free of empirical formulas or constants. Dimensionless closed-form solutions are derived for (1) the distributed (Winkler) springs and dashpots along the pile; (2) dynamic stiffness and damping coefficients at the pile head; (3) active length, beyond which the pile can be treated as infinitely long; and (4) relative contributions to the overall head stiffness and damping of the soil and the pile media. Swaying, rocking, and cross swaying-rocking impedances are considered for parabolic, exponential, and multilayered inhomogeneous soil. The predictions of the model compare favorably with established solutions, while new results are presented. An illustrative example is provided.
Original languageEnglish
Article number04016113
Number of pages19
JournalJournal of Geotechnical and Geoenvironmental Engineering
Issue number4
Early online date28 Oct 2016
Publication statusPublished - Apr 2017


  • Closed-form solution
  • Damping
  • Pile
  • Radiation damping
  • Soil-structure interaction
  • Stiffness


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