An experimental study on the pullout mechanical property of tortuous roots manufactured from 3D printing
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摘要:
天然根系具有不同弯曲形态，对根土相互作用特性影响极大。以往研究多将根系视为顺直，未充分考虑弯曲根系拉拔受力变形特征、破坏模式。利用3D打印技术制作弯曲根系，开展3种根径（2.0，3.5，5.0 mm）、5种弯曲度（1.00，1.05，1.10，1.15，1.20）的根系拉伸、拉拔试验，探索弯曲根系的拉拔力学特性。结果表明：根系拉伸特性受到弯曲结构和自身材料性质共同影响，根系最大拉伸力、拉伸变形刚度随弯曲度增加而减小，随直径增加而增大；根系峰值拉拔力随弯曲度增加呈先增大后减小，弯曲度1.15时最大，峰值拉拔位移呈类似变化趋势；弯曲根系齿肋挤压土体形成啮合作用，有助于增强根土相互作用；弯曲细根系的拉伸力和拉伸刚度低，更容易与土体协同变形承担拉拔荷载。弯曲根系受力变形与直根系差异极大，研究结果可为弯曲形态根系固土评价提供理论参考。
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.
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Key words:
- 3D printing /
- tortuous root /
- pullout test /
- root-soil interaction /
- peak pullout force
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表 1 弯曲根系的形态参数
Table 1. Morphological parameters of tortuous roots
试样 根系直径/mm 根系弯曲总长度/mm 根系弯曲度 S1 2.0，3.5，5.0 100 1.00 S2 1.05 S3 1.10 S4 1.15 S5 1.20 
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表 2 土体的物理特性指标
Table 2. Physical characteristics of soil
干密度
/（g∙cm−3）含水率
/%粒径分布/% <0.075 mm 0.075～
<0.25 mm0.25～
<0.5 mm0.5～
<1 mm1～
2 mm1.45 15.0 3.53 39.61 22.94 18.02 15.90
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