Discrete element modeling and experimental validation of the multi-scale based coronal tea plant root-soil complex

• The discrete element model of tea root-soil complex was developed. • The model reflects the multiscale nature of the structural differences of tea plant root. • Field experiments validated the engineering feasibility of the model. To clarify the internal kinematic and dynamic mechanisms in the root-soil interaction system, a high-fidelity discrete element model of the tea root-soil complex has been developed. The consistency in shape, distribution, and dimensions between the virtual geometry model and the actual coarse root was ensured through reverse engineering using 3D scanning to generate three-dimensional point clouds. Due to the non-uniform diameters and profiles of the coronal tea root, a micro-scale parallel particle filling strategy was adopted to address potential mechanical distortions. Furthermore, a disordered particle arrangement method was employed to prevent singularities arising from nonlinear structural features and to eliminate model failure caused by particle overlap. The mechanical accuracy of the discrete element model was validated through calibration and verification tests. Calibration tests consisted of a series of standardized tests, including density measurement, restitution coefficient test, repose test, and direct shear test. Verification tests were conducted both in the laboratory with a single root pull-out experiment and in the field to assess the soil complex’s reaction during the tillage process. Both the mechanical performance and the reinforcement effect demonstrated that the established root-soil discrete element model exhibited a high degree of consistency with real conditions, as verified by experiments in both the laboratory and the field. The proposed methodology for discrete element modeling of the woody plant root-soil complex offers a potential method for modeling woody roots at similar scales and provides theoretical support for understanding the interactions between soil-engaging components and the root-soil complex during tillage operations in tea plantations.