Experiments and modelling of horizontal loading tests on small-scale foundations in sand

The accurate prediction of settlements of shallow foundations under operational conditions is still an open issue for both scientists and engineers, in particular in the case of complex loading conditions (e.g. combined vertical and horizontal loads). The complexity of the soil mechanical response and the difficulty in managing a multiscale problem (ranging from the local scale of the soil representative elementary volume to the macro-scale of the structure) makes a rigorous modelling of such problems particularly demanding for standard numerical tools such as three-dimensional finite-element codes. In this perspective, the well-known macroelement approach may represent a valid simplified approach, capable of overcoming these limitations and allowing a comprehensive description of both serviceability limit state and ultimate limit state of such systems, particularly useful even for practitioners. In the paper, based on a small-scale 1g experimental campaign on a strip foundation, the effect of embedment is investigated over horizontal loading paths at a constant vertical load. In particular, relatively low vertical stress values are considered for the foundations, as it often happens in real structures under usual working conditions. A simple macroelement plastic model, based on a strain hardening law with non-associated flow rule is then proposed and validated over the available experimental data.