多花木蓝根截面微观结构对其抗拉特性的影响

根截面微观结构由连通的骨架和相互贯通或封闭的孔洞构成, 其与根系抗拉力学特性有密切的联系。该文通过单根拉拔测试根系力学特性并采用扫描电镜获取根截面微观特征, 探讨根截面微观结构特征与根抗拉力学特性的关系。主要结果显示: 1)根系截面单位面积承受拉力和拉伸应变的能力均随根直径的增大而降低。2)根系抗拉强度和韧性随平均孔径的增加而降低, 其次孔径的均匀性对二者也存在一定的影响。3)导管排列方式随根直径的增加, 呈现单管孔→复管孔→管孔链→管孔团的排列方式, 导管排列方式和分布均匀性对根抗拉力学特性都有影响, 其中排列方式较分布均匀性的影响大。4)根截面管孔面积比对根抗拉特性的影响还受木质部和根皮及导管特征的影响。该研究从根系微观结构的角度揭示了根直径的增大影响截面微观结构进而影响根系的抗拉力学特性, 为进一步解析灌木根系固土力学机制提供了一定的理论基础。

Effect of microstructure in cross section on tensile properties of Indigofera amblyantha

Aims The microstructure of root in cross section is composed of connected skeleton and interconnected or closed holes, which is closely related to the tensile mechanical properties of root system.
Methods The relationship of the microstructure of root in cross section and the tensile performances of root, in this study, was discussed by means of single root drawing test and scanning electron microscope (SEM).
Important findings The main results showed that: 1) the ability of root in cross section to bear tension and tensile strain decreased with the increase of root diameter in per unit area; 2) the tensile strength and ductile behaviors of root decreased with the increase of average pore size, and the uniformity of pore size also had a certain influence on them; with the increase of root diameter, the arrangement mode of vessels presents: single vessel → multiple vessel → chain of vessel → cluster of vessel. The arrangement mode of vessel and the uniformity of distribution have influences on the tensile strength characteristics of root, the influence of the arrangement mode has a greater influence than the uniformity distribution; 4) the influence of area ratio of root in cross section on root tensile properties, is also influenced by xylem, root bark and vessel characteristics. In conclusion, this study revealed that the increase of root diameter influenced the microstructure in cross section and affected the tensile properties of roots from the perspective of root microstructure, which provided a certain theoretical basis to further analysis of the soil fixation mechanism of shrub root systems.