A 3D root system morphological and mechanical model based on L-Systems and its application to estimate the shear strength of root-soil composites

Plant roots can strengthen soil significantly. This study aimed to develop a high-fidelity 3D root system morphological model for the mechanical analysis of root-soil composites. Furthermore, this model was used to investigate the shear strength behavior of root-soil composites as a function of growth time and shearing depth under saturated conditions. The developed model MechRoot is based on L-Systems implemented in MATLAB. The morphological and mechanical parameters were obtained by testing Lolium perenne roots. The shear strength of root-soil composites was obtained by conducting laboratory direct shear tests. MechRoot was applied to simulate Lolium perenne roots for different growth times and was imported into FLAC3D to simulate direct shear tests of root-soil composites at different depths. The model of the Lolium perenne roots built by MechRoot works well in mechanical analysis, and the simulation results are comparable to the laboratory direct shear test results. The shear strength of Lolium perenne root-soil composites shows an S-shaped curve versus the growth time. In addition, the shear strength first increases and then decreases with increasing depth. This study developed and validated a new tool for simulating the mechanical behavior of root-soil composites. Furthermore, an innovative understanding of root-soil composite shear behavior is presented.