Abstract
Purpose: To understand the mechanical role of plant roots in slope stabilization, a number of root reinforcement (RR) models, which differ greatly in form, mechanism and prediction, have been developed over the past half-century. This study aims to review RR modelling and models at individual root and bundle scales for tension-dominant roots in soil.Method: Through literature review, I show the similarities and disparities among models in the Wu and Waldron Model (WWM) family and the Fibre Bundle Model (FBM) family, and clarify some misunderstandings or citation bias in the literature. In particular, for the first time I put forward an RR model classification using a combination of criteria, including root failure order, root failure mode, load-sharing law, root diameter variation, root orientation ratio and correction factor.Results: Wu and Waldron, the two pioneering RR modellers, developed their own RR models in different ways and following contrasted concepts. FBM-family models have been deeply impacted by WWM-family models and continually diversified. Analytical derivation and uncertainty analysis show significant advantage in exploring the potential of RR models.Conclusions: The review and RR model classification may help future modellers and practitioners to better understand the state of the art in this field and the major features of these RR models. Future studies on RR models should focus more on validating load-sharing laws, examining the effect of root diameter distribution on RR estimation, incorporating multiple root mechanical behaviours, exploring RR prediction in the case of mixed species, and conceiving new paradigms compatible with both fine and coarse roots.