Abstract: This paper introduces the current understanding of stress strain behaviour of soils at small strains and a state of the art soil model the “bricks on strings” model. This model has the ability to mimic the soil behaviour at small strains. The key features of small strain soil behaviour include dependency of soil stiffness on strain magnitude and on recent stress history (stress states and stress paths). These imply that many soils are inelastic even at small strains. The “bricks on strings” model is subsequently used to back-analyse an urban deep excavation in stiff clay. Computed results are in good agreement with field measurements.