Discrete element modelling of the yam root–soil complex and its verification

This paper constructs a discrete element simulation model of yam based on a bimodal model and uniform grid coordinates and performs parameter calibration on the simulation model based on three mechanical properties. The bonding parameters are: normal stiffness per unit area 8.0684 × 107 N·m−3, shear stiffness per unit area 2.0314 × 107 N·m−3, critical normal stress 1.2876 × 107 Pa and critical shear stress 8.9623 × 107 Pa. Using the root–soil complex shear test, based on the grey correlation analysis method, a root morphology index with the greatest correlation with the maximum shear force of the yam root–soil complex was obtained. The factor that has the greatest influence on the maximum shear force of the root–soil complex is the total surface area of the root, the correlation degree is 0.77. The root–soil complex bond parameters are as follows: normal stiffness per unit area 5.203 3 × 105 N·m−3, shear stiffness per unit area 2.493 8 × 106 N·m−3, the critical normal stress 1 × 105 Pa and the critical shear stress 5.319 0 × 105 Pa. The accuracy of the simulation model of the yam root–soil complex was verified by comparing the simulation test with the physical test. The relative error of the axial compression rupture pressure value of the yam root–soil complex simulation test and the physical test is 6.63%, the relative error of the displacement value is 8.83%, the relative error of the radial compression rupture pressure value is 6.83%, and the relative error of the displacement value is 6.38%.