Impedance functions of end-bearing inclined piles

In this work, stiffness and damping functions of pile foundations with inclined end-bearing piles have been computed for square 2 x 2 and 3 x 3 pile groups embedded in a soft stratum overlaying a rigid bedrock. Results are presented in a set of dimensionless plots for two values of pile-soil stiffness ratio, three rake angles (10 degrees, 20 degrees and 30 degrees, together with the vertical case) and three different directions of inclination of the piles with respect to the excitation. The paper also investigates the influence that the assumption of a perfectly rigid bedrock and fixed boundary conditions at the pile tips have on the impedance functions. Stiffness and damping coefficients of batter pile groups embedded in a half-space are also displayed for reference, and the more important features of the presented curves are discussed. The fundamental frequencies of the soil layer are clearly reflected in the impedance functions, but additional resonances, related to phenomena involving both soil layer resonance and pile-to-pile interaction, are also observed in the horizontal mode for higher frequencies. (C) 2012 Elsevier Ltd. All rights reserved.