云南省东川银合欢林区重塑土三轴抗剪强度实验研究

为研究固氮植物的固土机制,在中国科学院东川蒋家沟泥石流观测研究站银合欢林区选取5棵树龄相当的银合欢树,于植株附近1m处分别挖取深2m,宽1m的土壤剖面取土并采取银合欢树根,对含有银合欢树根的重塑土进行三轴实验。分析了抗剪强度、黏聚力及内摩擦角与含根量及根径的关系。实验结果表明,抗剪强度与含根量及根径均呈正相关,黏聚力与含根量及根径均呈正相关,内摩擦角受含根量及根径的影响较小,在一定程度上呈负相关。准黏聚力准则与该实验结果一致,同时也存在不同之处,即随着含根量的增多及根径的增大,土体的黏聚力提高,但在一定程度上土体内摩擦角有所降低。定量评价银合欢根系在提高土体抗剪强度方面所起的作用,对利用生物工程措施在该区域进行生态修复有着重要的应用价值。

Tri-axial Experimental Analysis of Shear Strength of Regenerated Soil in Leucaena Forest of Dongchuan Area of Yunnan Province

In order to understand soil reinforcement mechanisms of nitrogen-fixing plants,we chose five Leucaena trees with similar ages in Jiangjia Ravine of Dongchuan area of Yunnan Province,near which soil samples were collected on profiles of 2 m deep and 1 m wide.Soil and roots of Leucaena trees were taken for tri-axial experiments to determine the relationship among shear strength,cohesion,friction angle,root amount,and root diameter.It was found that both shear strength and cohesion related positively to the amounts and diameters of the roots.Meanwhile,the amounts and diameters of the roots negatively related to friction angles,to less extent.The results of tri-axial experiments agreed well with the cohesion principles.The cohesion of soil was enhanced by the roots;however,the friction angle of soil was degraded at the same time.According to the quantitative assessment on the roots of Leucaena trees in improving shear strength of soil,more attention should be paid to applying biological engineering measures to ecological restoration of this region.