Centrifuge modelling of vegetated soils: A review

Abstract

Understanding the soil–root mechanical interaction is crucial to advancing the utilisation of vegetation as a nature-based approach to designing more stable slopes and resilient urban forestry against tree windthrown. Although numerical and analytical models for detailed analysis of soil–root interaction exist, these models are seldom validated due to the lack of field data and the significant challenges in quantifying such interactions due to the complex nature of root system. The centrifuge modelling technique is an effective alternative for unravelling the complexities of the hydromechanical behaviour of vegetated soils by recreating prototype stress levels in small-scale physical models and testing them under more controlled conditions. This work presents a critical review on existing centrifuge modelling methods for vegetated soils, paying particular attention on the (i) fundamentals of centrifuge modelling, where principles, scaling laws and applications relevant to modelling vegetated soils are detailed; (ii) methods for modelling soils, including choice of soil material and sample preparation; and (iii) methods for modelling roots by means of natural plants and root analogues, where the replication of root morphology, mechanical properties and capabilities of modelling transpiration effects are discussed. In every topic, the challenges that could further advance the centrifuge modelling of vegetated soils and the possible ways to address them are highlighted. Finally, the prospect for future studies is discussed, highlighting the potential to enhance the understanding of the underlying mechanisms amongst plant roots, soil, water and external loading.