Axial kinematic response of end-bearing piles to P waves

摘要

Kinematic pile-soil interaction under vertically impinging seismic P waves is revisited through a noveludcontinuum elastodynamic solution of the Tajimi type. The proposed model simulates the steady-stateudkinematic response of a cylindrical end-bearing pile embedded in a homogeneous viscoelastic soil stratumudover a rigid base, subjected to vertically-propagating harmonic compressional waves. Closed-form solutionsudare obtained for: (i) the displacement field in the soil and along the pile, (ii) the kinematic Winkler moduliud(i.e., distributed springs and dashpots) along the pile, (iii) equivalent, depth-independent, Winkler moduli toudmatch the motion at the pile head. The solution for displacements is expressed in terms of dimensionlessudtransfer functions relating the motion of the pile head to the free-field surface motion and the rock motion. Itudis shown that: (a) a pile foundation may significantly alter (possibly amplify) the vertical seismic excitationudtransmitted to the base of a structure; and (b) Winkler moduli pertaining to kinematic loading differ fromudthose for inertial loading. Simple approximate expressions for kinematicWinkler moduli are derived for use in applications