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

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。

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.