Physical modelling of soil-structure interaction of tree root systems under lateral loads

This paper presents some initial physical modelling of root-soil interaction for trees under lateral loading, such as from wind or debris flows. 3-D printing of interconnected systems of ABS plastic root analogues, which are mechanically representative of tree roots, is used to produce idealised root architectures with varying root depth, spread and root area ratio (RAR, i.e. amount of roots). These models are installed within a granular soil with a wooden model trunk attached and laterally loaded to measure the push-over behaviour. From this data, the moment capacity and rotational stiffness of the model root systems are evaluated. The results suggest that (i) the effect of the central tap root on strength and stiffness is low, compared to the lateral and sinker roots, but otherwise proportional to RAR; and (ii) that development of analytical predictive models may be able to adapt existing procedures for conventional geotechnical systems, such as pile groups.