An experimental study on the pullout mechanical property of tortuous roots manufactured from 3D printing

Abstract

Natural roots systems exhibit various tortuous morphologies, which significantly impact the root-soil interaction characteristics. Previous studies often treated root systems as straight, neglecting the deformation characteristics and failure modes of tortuous root systems under tensile loads. In this study, tensile test and pullout test are conducted by using tortuous roots manufactured from 3D printing technology with three different root diameters (2.0, 3.5 and 5.0 mm) and five root tortuosity (1.00, 1.05, 1.10, 1.15, 1.20), and the pullout behaviours of tortuous roots are explored. The results indicate that the tensile properties of root systems are influenced by both the tortuous structure and the material properties. The ultimate tensile force and tensile stiffness decreases with increasing tortuosity but increase with increasing diameter. The peak pull-out force of the root system initially increases and then decreases with tortuosity, reaching a maximum value when tortuosity is equal to 1.15. The peak pull-out displacement shows a similar trend. The tortuous root system forms an engaging effect with the soil by compressing the soil ribs, enhancing the interaction between roots and soil. The tensile force and stiffness of the tortuous fine root system are low, making it more prone to coordinate deformation with the soil to bear tensile loads. The deformation under stress of tortuous root systems differs significantly from that of straight root systems. This study provides theoretical references for the evaluation of soil-reinforcement by root system.

Keywords

• 3d printing
• tortuous root
• pullout test
• root-soil interaction
• peak pullout force