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

A finite element study has been carried out to determine the pile-soil-pile interaction behaviour for closely spaced pile rows and groups under passiv e lateral loading from soil movement. A horizontal section close to the pil es was studied to determine the effects of pile spacing and soil constituti ve law on the load-transfer relationships of the piles. The study has revea led links between the soil stress-strain law, the soil deformation mechanis m and the pile load-transfer curves. Interaction behaviour was seen to depe nd on the prevailing deformation mechanism which in turn was governed by th e soil constitutive law. Elastic-plastic and power law soil models were app lied. Interaction factors suitable for design use to account for increasing lateral pressure on piles during passive lateral loading have been produce d for a range of pile spacings and power law soil exponents. Interaction be tween piles increased both with reduction of pile spacing and with increase of soil exponent-the less soil stiffness degradation with shear strain, th e greater the interaction between piles at a given spacing. This suggests t hat the passive interaction factors calculated using elastic methods are li kely to overestimate the effects of pile-soil-pile interaction. : (C) 1999 Elsevier Science Ltd. All rights reserved.