基于不同根截面比的根-土复合体室内直剪试验

Indoor Direct Shear Test of Root-soil Composite Based on Different Root Area Ratio

植被根系可显著提升土体抗剪强度。为量化小叶女贞根系对土体抗剪强度的贡献,以直径为2mm的小叶女贞根系-土复合体为研究对象,对不同根系分布形式与RAR(根截面比)的根-土复合体采取一系列直剪试验,并基于Mohr-Coulomb准则建立根-土复合体剪切力学模型。结果表明:根-土复合体的主体仍为土体,可适当忽略根-土界面摩擦角带来的土体内摩擦角变化;根系可明显提高根-土复合体抗剪强度,且法向应力和RAR较小时增强抗剪能力更显著;黏聚力随着RAR的增大呈现出相同的变化趋势,而内摩擦角受RAR影响较小,与模型预测一致。研究成果可为根系固土植被选择提供参考。

Vegetation root can significantly enhance the shear strength of soil.In order to quantify the contribution of the root system of Ligustrum quihoui to the shear strength of soil,a 2 mm diameter Ligustrum quihoui root-soil composite was studied.A series of direct shear tests were conducted on root-soil composite with different root distribution forms and RAR(root area ratio),and a shear mechanical model of the root soil composite was established based on the Mohr-Coulomb criterion.The results show that the main property of the root soil composite is still the soil,and the changes in the internal friction angle of the soil caused by the friction angle at the root soil interface can be appropriately ignored.The root system can significantly improve the shear strength of root-soil composite,and the shear resistance is more significantly enhanced when the corresponding stress and RAR are small.The cohesive force gradually increases with the increase of RAR,while the internal friction angle is less affected by the root system,which is consistent with the model prediction.The research results provide reference for the selection of root fixed soil vegetation.