根系逐渐破坏过程中固土效果研究  

Change of soil fixation effects in the process of gradual damage

作　　者：郭翬 王云琦[1] 王青兰[2] 王玉杰[1] 张会兰[1] 王彬[1] 朱锦奇[1] 李云鹏[1] 

机构地区：[1]北京林业大学水土保持学院,水土保持与荒漠化防治教育部重点实验室 [2]山西水利职业技术学院

出　　处：《北京林业大学学报》2015年第6期85-92,共8页Journal of Beijing Forestry University

基　　金：北京高等学校青年英才计划项目(YETP0751)

摘　　要：植物根系的固土效果会随根系破坏而发生变化,但其变化过程并不明确。以重庆缙云山的四川山矾为研究对象,以2 mm为根系径级,采用逐径级剪除根系法模仿根系逐渐遭到破坏的过程;同时测量根系的抗拉与抗拔强度,利用自制大盒直剪仪测量根土复合体的抗剪强度,并与Wu模型计算值作对比,系统研究根系逐渐破坏过程中的固土效果。结果表明,春季生四川山矾3年幼苗的植物根系抗拉强度随着根系直径的减小而减小。当根系直径小于2 mm时,根系拉拔强度要高于植物根系的抗拉强度,当根系直径大于2 mm时,则根系抗拉强度更大。大盒直剪测量结果显示,根系破坏过程中根土复合体的抗剪强度首先保持不变,当大于2 mm的根系开始与土壤分离时,根土复合体的抗剪强度会快速下降。在一定范围内,根面积比越大,根土复合体的抗剪强度越大,根系对土壤的加固作用越强。在根系逐渐破坏过程中,Wu模型在一定程度上高估了根土复合体的抗剪强度,且高估值与根面积比呈正相关关系。The effects of fixing soil by plant roots vary when roots are damaged; however, the mechanical process remains unclear. In this study, Symplocos setchuensis in Jinyun Mountain of Sichuan Province was used as research object. Using 2 mm as root diameter class, we gradually cut off roots in each class to simulate the process of roots being gradually damaged. Simultaneously, the root tensile and pull-out strength were measured by an electronic pulling force machine, and the shear strength of the root-soil composite （RSC） was measured with large direct shear test. The measured results were compared with calculated values of the model developed by Wu （1976）, so that the effect of soil fixation of roots in the process of gradual damage to them was systematically explored. Results showed that the tensile strength of 3-year-old S. setchuensis seedlings growing in spring decreased with the decrease of root diameter. Tensile strength works mainly in roots with diameter less than 2 mm. Pull-out strength is the major power in roots with diameter larger than 2 mm. Results from large direct shear test indicated that the shear strength of RSC was consistent in the initial stage of root damage, and it declined rapidly when the roots with diameter larger than 2 mm were separated from the soil. Moreover, the larger the RAR （root area ratio） is, the greater the shear strength of RSC is, and the stronger the effect of soil fixation is. However, to a certain degree, Wu＇s model overestimates such effect and the overestimated parts have a positive correlation with RAR.

关 键 词：四川山矾 根系破坏 固土效果 大盒直剪 拉拔强度 Wu模型 

分 类 号：S714.7[农业科学—林学]