为了研究露天矿排土场草本植物根系的加固效果,以当地生长的早熟禾、碱蓬和马唐3种草本植物为研究对象,通过植物根系的抗拉强度试验、原位剪切试验和Wu-Waldron模型(WWM)计算,确定WWM模型修正因子,进而采用修正后的WWM模型,结合不同深度土壤剖面上植物根系的几何分布特性,量化排土场草本植物根系的黏聚力。结果表明:3种草本植物根系的抗拉强度与直径呈现幂律函数关系,抗拉强度均随植物根系直径的增大而非线性减小,3种草本植物根系的抗拉强度存在显著性差异(p<0.05);马唐根系加固下,根土复合体存在更大的抗剪力,且在峰值剪力后,马唐根系加固的根土复合体最稳定;WWM模型高估了植物根系的加固效果,高估的程度因物种的不同而不同,对3种草本植物根系加固的WWM模型进行修正,早熟禾、碱蓬与马唐根系的修正因子分别为0.58、0.27和0.88;3种草本植物根系面积比与根系黏聚力均随着土壤深度的增加而减小;马唐根系在当地的加固效果最优。
Abstract
The aim of this study is to investigate the reinforcement effect of herbaceous plants in opencast mine dump area. Three locally grown herbaceous plants, Poa annua L., Suaeda glauca Gunge, and Digitaria sanguinalis Scop. are selected as research objects. Through tensile strength test and in-situ shear test on plant roots as well as Wu-Waldron model (WWM) calculations, the correction factor of WWM model is determined, and then the corrected WWM model is used to quantify the root cohesion of herb plants in the dump site in association with the geometric distribution characteristics of roots on soil profiles at different depths. Results demonstrate that the tensile strength of the three herbaceous plants has a power-law function relationship with root diameter, decreasing nonlinearly with the increase of diameter. Significant (p<0.05) differences are found in the tensile strength of the three herbaceous plants. In comparison, the root-soil composite reinforced by Digitaria sanguinalis Scop. provides larger shear resistance, and also greater stability after peak shear force. WWM model overestimates the reinforcement effect of plant roots, and the degree of overestimation varies with species. Moreover, the WWM model for the three herbaceous plants are modified, and the correction factors are 0.58, 0.27 and 0.88, respectively. Both the root area ratio and root cohesion of the three herbaceous plants decrease with the increase of soil depth. Digitaria sanguinalis Scop. has the best reinforcement effect in the local area.
关键词
草本植物加固 /
排土场 /
根系黏聚力 /
根土复合体 /
原位剪切试验
Key words
herbaceous plant reinforcement /
dump site /
root cohesion /
root-soil composite /
in-situ shear test
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基金
国家重点研发计划项目(2017YFC1503101,2017YFC1503102)
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