四川山矾根系分支节点对根系固土效益的影响

doi:10.11707/j.1001-7488.20210212

摘要/Abstract

摘要：

目的: 研究根系形态学参数和力学参数对固土效果的影响，进一步了解根-土相互作用机制和固土机制。方法: 利用改装过的万能试验机测定四川山矾根系的抗拉强度、杨氏模量、摩擦力等力学特性，利用自制的大盒直剪装置测定含根土样本的抗剪强度。分析根系形态学参数与力学特性参数的关系。结果: 1）四川山矾的根直径与根长、抗拉强度、杨氏模量和拔出力都符合幂函数关系。其中，根直径与抗拉强度和杨氏模量呈负相关，根直径与根长、拔出力呈正相关。2）四川山矾根系分支节点数的增加，可显著提高根系拔出力，但分支节点对单位根长度拔出力的影响较小。3）四川山矾根系分支节点的增加，可显著提高根系的土壤加固效果，每存在1个分支节点可提高根系附加抗剪强度约50%。分支节点的增加可显著提高单位根长和根直径的附加抗剪强度。4）主成分分析发现，对根系附加抗剪强度的极值影响最大的参数为根长之和，而对根系附加抗剪强度的屈服值影响最大的参数为根直径之和。结论: 四川山矾根系分支节点的存在对根系的拔出强度和最终的固土效果都有显著影响，是根系固土效果定量研究中的重要参数，这对理解和分析边坡植物根系加固土壤的机制有重要意义。

关键词: 根直径, 根长, 根系分支节点, 拔出力, 抗剪强度

Abstract:

Objective: The objective of this study is to qualify the effect of root architecture and mechanical traits on root soil reinforcement, and further understand the mechanism of the root-soil interactions and soil consolidation. Method: The tensile strength, Young's modulus, friction and other mechanical characteristics of root system of Symplocos setchuensis were measured with a modified universal testing machine. Furthermore, the shear strength of root soil samples was measured by self-made large box direct shear device, in order to find out the multiple relationships between root architecture, mechanical, and soil reinforcement traits. Result: Firstly, there was a power function relationship between the root diameter of S. setchuensis with root length, tensile strength, Young's modulus, as well as pullout force. Among them, the root diameter was negatively correlated with root tensile strength, and Young's modulus, while the root diameter was positively related to root length and pullout force. Secondly, there was a strong positive relationship between root branching and pullout force. However, there was no significant statistical difference between the branching and pullout force per unit root length (or diameter). Thirdly, The increase of root branching nodes was able to significantly improve the soil reinforcement effect of root system, and each branching node could increase the additional shear strength of root system by about 50%. Moreover, the branching nodes also could increase the reinforcement effect per unit length and root diameter. Fourthly, Principal component analysis showed that root length was found strongly correlated with root reinforcement at the maximum point while diameter was strongly correlated with root reinforcement at yield point. Conclusion: The study quantified the positive influence of S. setchuensis root mechanical properties and branches on its resistance of pullout and soil shear behavior. This information is important to improve the accuracy of root reinforcement estimated and our understanding of root reinforcement mechanism.

Key words: root diameter, root length, root branch, pullout force, shear strength

中图分类号:

S774
S714.7

朱锦奇,王云琦,王玉杰,郑波福,李亦璞. 四川山矾根系分支节点对根系固土效益的影响[J]. 林业科学, 2021, 57(2): 115-125.

Jinqi Zhu,Yunqi Wang,Yujie Wang,Bofu Zheng,Yipu Li. Effects of Root Branch of Symplocos setchuensis on Root Soil Reinforcement[J]. Scientia Silvae Sinicae, 2021, 57(2): 115-125.

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土层 Soil layer/cm	土壤密度 Soil density/(g·cm^-3)	土壤紧实度 Soil compactness/kPa	土壤液限 Liquid limit (%)	土壤塑限 Plastic limit (%)	土壤有机质含量 Soil organic matter content/(g·kg^-1)
0~10	1.12 ± 0.22	42.64 ± 3.79	32.34	20.73	26.40 ± 13.94
10~30	1.30 ± 0.22	68.43 ± 6.67	34.51	21.84	18.63 ± 7.37
30~50	1.35 ± 0.19	78.91 ± 5.88	33.68	22.37	9.79 ± 4.61

分支节点数量 Noumber of root branches	拔出力均值 Average value of root pullout force/N	单位根长拔出力均值 Average value of root pullout force per root length/(N·m^-1)	附加抗剪强度均值Average value of root reinforcement/kPa
分支节点数量 Noumber of root branches	拔出力均值 Average value of root pullout force/N		屈服点Yield point	极值点Maximum point
0	367.77 ± 273.17	1.53 ± 0.56	1.00 ± 0.52	0.92 ± 0.46
1	769.10 ± 282.39	1.79 ± 0.37	1.41 ± 0.42	1.41 ± 0.38
2	950.06 ± 249.19	2.13 ± 0.26	1.83 ± 0.52	1.86 ± 0.49
3	909.28 ± 171.44	2.06 ± 0.20	2.12 ± 0.51	2.09 ± 0.41
4	1 278.57 ± 264.46	2.27 ± 0.27	2.74 ± 0.38	2.95 ± 0.41

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