Soil-Structure InteractionE.H. Davis Memorial Lecture 2001

John C. Small

The term “soil-structure interaction” can refer to a wide range of topics, including the behaviour of buried pipes, tunnel linings and conduits, retaining structures as well as the interaction between a building and its foundation. In this article, the scope will be restricted to foundations for buildings that may consist of surface raft foundations or deep foundations such as piled raft foundations.

Because structures have been traditionally designed by structural engineers and foundations by geotechnical engineers, there has tended to be a separation of design work into that of the structure and that of the foundation. Either the stiffness of the structure is neglected and uniform loads are applied to the soil surface, or the structure is analysed alone and the soil is treated as a series of springs representing the foundation soil. In the case of a piled raft, the piles supporting the raft are often treated as springs. Neither approach is satisfactory, and some form of interaction analysis is warranted to take the structural stiffness into account.

Much of the pioneering work in this area was carried out in Australia by Fraser and Wardle (1976), Hain and Lee (1974, 1978), Poulos and Davis (1980) and Brown (1969a,b) to name a few. The development of methods for the analysis of soil-structure interaction involving foundations has developed a great deal since this early research and convenient accounts can be found in the books by Hemsley (1998, 2000). Solution methods range from simple hand calculation techniques to semi-analytical and numerical methods that require complex computer analysis. Each type of analysis has its field of application and, in general, simple techniques can be used in the early stages of design to obtain some understanding of foundation behaviour before more complex analysis is undertaken.