Macroelement modelling

Numerical modelling using a full finite element or finite difference analysis may be ultimately necessary but may be a heavy-handed way of seeking insight into some aspects of a problem of geotechnical behaviour. Theoretical modelling may only be possible for rather restricted problems. Macroelement modelling may be a helpful intermediate way of introducing some realistic geotechnical nonlinearity in order, for example, to compare different constitutive possibilities or perhaps just to provide a rapid 'order-ofmagnitude' estimate of response against which the results of more extensive numerical modelling—or physical modelling—can be compared. Equally, physical or numerical modelling may itself provide clues concerning mechanisms of system response which may suggest ways in which simple macroelement models might be devised. It will be seen that this has indeed been the route for the development of some of the macroelement models outlined here. We will describe three examples of analysis of soil-structure interaction using a macroelement approach. Two of these are closely related — the lateral deflection of a pile or pipeline or tunnel as the surrounding ground moves. The third is a dynamic analysis of a gravity retaining wall.