Approximate computer analysis of pile groups subjected to loads and groundmovements

This paper describes the development of an approximate approach far the ana lysis and design of piles subjected to axial and lateral loading and also t o vertical and horizontal ground movements. The analysis involves a number of simplifications in order to make it feasible to implement. For example, it considers the behaviour of a 'representative' pile in a group to charact erize the behaviour of all piles in the group, and adopts approximations to derive free-field interaction factors from the conventional interaction fa ctors for direct loading. The analysis has been implemented via a computer program called EMbankment PIle Group (EMPIG) and has the ability to incorpo rate the following features: 1. single piles or pile groups, 2. applied vertical, lateral and moment loading on the pile cap, 3. the effects of axial and lateral soil movements caused by embankment con struction, 4. a layered soil profile, 5. non-linear axial and lateral response of the piles. Comparisons between solutions from EMPIG and other independent programs sug gest that it is capable of providing results of adequate accuracy for pract ical design purposes. The analysis has been used to investigate the effects of pile rake on a typ ical bridge abutment group. The presence of raked piles can have a detrimen tal effect on group behaviour, especially in the presence of ground movemen ts. Large lateral deflections can be generated and axial forces and moments in the piles are increased. Comparisons are also made with the results of centrifuge model tests on abutment pile groups. Copyright (C) 1999 John Wil ey & Sons, Ltd.