灌木根系形态对土体强度影响的大型直剪试验研究

doi:10.11988/ckyyb.20230573

院报 ›› 2024, Vol. 41 ›› Issue (8): 120-127.DOI: 10.11988/ckyyb.20230573

灌木根系形态对土体强度影响的大型直剪试验研究

陈婧逸¹^,²(), 陈晓清¹^,²(), 宋东日¹^,², 吕明¹^,², 蒋豪¹^,²

¹ 中国科学院、水利部成都山地灾害与环境研究所山地灾害与地表过程重点实验室,成都 610299
² 中国科学院大学,北京 100049

收稿日期:2023-05-24 修回日期:2023-08-01 出版日期:2024-08-01 发布日期:2024-08-13
通讯作者: 陈晓清(1974-),男,四川成都人,研究员,博士,研究方向为山地灾害防治。E-mail: xqchen@imde.ac.cn
作者简介:
陈婧逸(1998-),女,河北衡水人,硕士研究生,研究方向为边坡生态防护。E-mail: chenjy@imde.ac.cn
基金资助:
国家自然科学基金项目(41925030)

Effect of Shrub Root Morphology on Root-Soil Complex Strength: A Study Based on Large-scale Direct Shear Test

CHEN Jing-yi¹^,²(), CHEN Xiao-qing¹^,²(), SONG Dong-ri¹^,², LÜ Ming¹^,², JIANG Hao¹^,²

¹ Key Laboratory of Mountain Hazards and Earth Surface Processes, Institute of Mountain Hazards and Environment, CAS, Chengdu 610299, China
² University of Chinese Academy of Sciences, Beijing 100049, China

Received:2023-05-24 Revised:2023-08-01 Published:2024-08-01 Online:2024-08-13

摘要/Abstract

摘要：

根系形态显著影响根土复合体强度,然而现有研究局限于草本根系根土复合体和室内常规直剪试验。为探究多年生灌木根系形态及空间分布对固土效果的影响,采用大型直剪试验装置(直径400 mm),对原状根土复合体进行了剪切试验。试验中测量了根系形态参数(根面积比RAR、根长密度、根体积密度和根表面积密度)、根土复合体抗剪强度和剪胀特性,探讨了根系沿深度的分布特征、根土复合体剪胀性以及根系形态参数与根土复合体抗剪强度的相关关系。结果表明,根系加剧了根土复合体的剪胀;在4个根系形态参数中,剪切带上的RAR和根表面积密度与根系对剪切强度的贡献之间相关性较好;Wu模型能反映根系固土的本质,却存在强度被高估或低估的问题。研究成果有助于推动植物根系在固土领域的应用。

关键词: 灌木根系形态, 根土复合体, 抗剪强度, 剪胀, 大型直剪

Abstract:

The strength of root-soil complex is significantly influenced by the morphology and spatial distribution of the root system. However, current studies have been limited to shear tests of root-soil complexes containing herbaceous roots and conventional indoor direct-shear tests. To investigate the impacts of root morphology and spatial distribution of perennial shrubs on root reinforcement, shearing experiments were conducted on in situ root-soil complex using a large-scale direct-shear apparatus (diameter 400 mm). The root morphological parameters (root area ratio RAR, root length density, root bulk density, and root surface area density), dilatancy and shear strength of the root-soil complex were measured. The distribution characteristics of root system along soil depth, the dilatancy of root-soil complex, and the correlation between root morphological parameters and shear strength were examined. Findings indicate that the root system exacerbates the dilatancy of the root-soil complex. Among the four evaluated root morphological parameters, RAR and root surface area density contribute the most to the shear strength. While Wu’s model effectively reflects the enhancement effect of root system on soil strength, it occasionally overestimates or underestimates the strength. The findings in the present research is conducive to promoting the application of root system in soil reinforcement.

Key words: shrub root morphology, root-soil complex, shear strength, dilatancy, large-scale direct-shear test

中图分类号:

TU411.7土的抗剪强度试验

陈婧逸, 陈晓清, 宋东日, 吕明, 蒋豪. 灌木根系形态对土体强度影响的大型直剪试验研究[J]. 院报, 2024, 41(8): 120-127.

CHEN Jing-yi, CHEN Xiao-qing, SONG Dong-ri, LÜ Ming, JIANG Hao. Effect of Shrub Root Morphology on Root-Soil Complex Strength: A Study Based on Large-scale Direct Shear Test[J]. Journal of Yangtze River Scientific Research Institute, 2024, 41(8): 120-127.

图/表 11

表1 试验样品及特征参数

Table 1 Characteristics parameters of tested samples

试样编号	RAR/ %	含水率/ %	总根长/ (10³ mm)	总根体积/ (10³ mm³)	总根表面积/ (10³ mm²)
B		28.3
V1	0.395	28.6	143.4	236.1	345.1
V2	0.386	28.5	204.9	224.4	427.3
V3	0.436	28.9	215.3	232.6	458.1
V4	0.241	28.8	114.0	132.6	245.4

图1 试验仪器

Fig.1 Apparatus used in the test

图2 剪切结束后的试样V3

Fig.2 Sample V3 after shearing

图3 紫穗槐根系

Fig.3 Root system of Amorpha fruticose

图4 根系长度、体积、表面积随深度的分布

Fig.4 Distribution of root length, volume and surface area with depth

图5 不同径级根系随深度的分布

Fig.5 Distribution of root system with depth for different diameter classes

图6 素土试样和含根试样的应力-应变曲线

Fig.6 Relationship between shear stress and strain for root-soil complex and bare soil samples

图7 根系提供的抗剪强度增量ΔSr与根系形态参数间的关系

Fig.7 Relationship between the shear strength incre-ment ΔSr provided by the root system and the morphological parameters of root system

图8 素土试样和含根试样的竖向应变-剪应变关系曲线

Fig.8 Curves of vertical strain versus shear strain of bare soil and root-soil complex samples

图9 剪切过程中剪胀角随剪应变的变化

Fig.9 Variation of angle of dilatancy with shear strain during shearing

图10 根系固土效果的实测值和预测值比较

Fig.10 Comparison of enhanced soil shear strength between modelling and test results

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灌木根系形态对土体强度影响的大型直剪试验研究

Effect of Shrub Root Morphology on Root-Soil Complex Strength: A Study Based on Large-scale Direct Shear Test

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