喀斯特地区灌木根系力学特性及WU模型适用性研究

植物根系力学特性(抗拉、抗剪)是决定水土保持的关键因素。为研究喀斯特地区灌木根系的护坡力学效应,以多花木蓝和双荚决明根系为研究对象,通过室内单根拉拔和根土复合体直剪试验,探讨单根拉伸特性与根土复合体剪切特性的关系,并探讨WU模型的适用性。结果表明:随根径的增加,抗拉强度总体呈下降趋势,因树种的不同,趋势不尽一致;单根抗拉强度和根土间的摩擦共同影响根土复合体抗剪特性,前者影响最大,后者的影响相对有限,以细根和粗根搭配使用较优;WU模型在喀斯特地区经修正可适用,但不同的植物具有不同的修正系数。研究结果将为喀斯特地区生态恢复、边坡绿化树种筛选及配置奠定良好的基础。

Mechanical Properties of Shrubs and Applicability of Model WU in Karst Area

The mechanical properties(tensile and shear properties) of roots are pivotal factors affecting the soil and water conservation. The roots of Indigofera amblyantha Craib and Cassia bicapsularis Linn were selected to research the mechanics of slope protection in Karst area. The relationship between the roots’ tensile strength and the shear characteristics of soil-root composite was investigated through indoor tensile test on single root and direct shear test on soil-root composite. The applicability of model WU in Karst area was also analyzed. Results indicated that tensile strength declined overall with the increasing of root diameter; however, such trend differs corresponding to different plant types. The shear characteristic of soil-root composite was jointly affected by tensile strength and friction between soil and roots, of which the former had larger influence; the shear characteristic with thin root and thick root together was better. Modified model WU is applicable to Karst area; but the modification coefficient varies corresponding to different plants. The research findings would lay a good foundation for the ecological restoration and selection and allocation of tree species in Karst area.