Vertical load transfer from pile group to multilayered Poroelastic medium

Abstract

This thesis studies load transfer from a vertically loaded elastic pile group to a multi­ layered poroelastic half-space. The pile group-poroelastic medium is decomposed into a group of one-dimensional fictitious elastic solids and an extended multi-layered poroelastic half-space. Each layer of the extended half-space is governed by Biot's theory of poroelasticity and the interaction problem is formulated in Laplace transform domain. The vertical displacement distribution of each pile is approximated by an exponential series with a set of arbitrary coefficients. Strain energy of the pile groups is expressed in terms of arbitrary coefficients. Displacement influence functions corresponding to a multi-layered half-space subjected to buried vertical patch loading are required in the formulation. They are obtained by employing an exact stiffness matrix method. Thereafter, strain energy of the extended half-space is expressed in terms of the unknown arbitrary coefficients. The minimization of total potential energy of the piles-half-space system yields a set of linear simultaneous equations to determine the arbitrary coefficients. Time domain solutions are obtained by using an appropriate numerical Laplace inversion scheme. Selected numerical results for vertically loaded pile groups in a multi-layered poroelastic medium are presented to portray the influence of the group configuration, the layering and the poroelastic material parameters on the quasi-static behavior of the pile group.