Recent field and laboratory studies have shown that, even at very small strains, many soils exhibit non-linear stress-strain behaviour. Nevertheless, because of its convenience, linear elasticity will continue to play an important role in the analysis of such problems as settlement, deformation and soil-structure interaction. In this Paper the measured non-liqear stress-strain properties of a low plasticity clay are used in the finite element analysis of footings, piles, excavations and pressuremeter tests to assess the influence of small strain non-linearity in comparison with linear elastic behaviour. 

In all cases non-linear behaviour results in the concentration of strain and deformation towards the loading boundaries. This is shown to have important consequences for soil-structure interaction problems such as settlement profiles, pile group interaction and contact stress distributions. Small Strain Nonlinearity also has a significant influence on the interpretation in terms of equivalent elastic moduli of in situ deformation tests