Selection of load–transfer functions for passive lateral loading of pile groups

Abstract

Abstract A finite element study has been carried out to determine the pile–soil–pile interaction behaviour for closely spaced pile rows and groups under passive lateral loading from soil movement. A horizontal section close to the piles was studied to determine the effects of pile spacing and soil constitutive law on the load–transfer relationships of the piles. The study has revealed links between the soil stress–strain law, the soil deformation mechanism and the pile load–transfer curves. Interaction behaviour was seen to depend on the prevailing deformation mechanism which in turn was governed by the soil constitutive law. Elastic-plastic and power law soil models were applied. Interaction factors suitable for design use to account for increasing lateral pressure on piles during passive lateral loading have been produced for a range of pile spacings and power law soil exponents. Interaction between piles increased both with reduction of pile spacing and with increase of soil exponent—the less soil stiffness degradation with shear strain, the greater the interaction between piles at a given spacing. This suggests that the passive interaction factors calculated using elastic methods are likely to overestimate the effects of pile–soil–pile interaction.