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| Microstructural features and friction characteristics of the interface of shrub roots and soil in loess area of Xining Basin#br# |
| LIU Yabin1，2，3，HU Xiasong1，4，YU Dongmei1，2，LI Shuxia1，2，3，YANG Youqing1，2，3 |
| (1. Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources，Qinghai Institute of Salt Lakes，Chinese Academy of Sciences，Xining，Qinghai 810008，China；2. Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes，Xining，Qinghai 810008，China；3. University of Chinese Academy of Sciences，Beijing 100049，China；4. Department of Geological Engineering，Qinghai University，Xining，Qinghai 810016，China) |
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Abstract Two 2-year-old shrubs Caragana korshinskii Kom. and Zygophyllum xanthoxylon Maxim.，which were planted in the testing area，were selected as the research objects. The scanning electron microscope (SEM) was applied to analyze the microstructural features of root surface，soil surface contacting the roots and soil surface not in touch with the roots，and to investigate their influence on the friction characteristics of the root-soil interface. The pull-out test of a single root was carried out to quantitatively evaluate the static friction coefficient and the friction resistance per unit area of the root-soil interface of two shrubs. The results of scanning electron microscope reveal that the roughness degree of root surface of C. korshinskii is higher than that of Z. xanthoxylon，that the soil surfaces contacting the roots of both shrubs are relatively flat and dense and that the soil surface not in touch with the roots is rough and porous. The soil surfaces contacting the roots can be flattened by the roots during the growth process so that the roughness degree of the soil surface contacting the roots is significantly reduced，which shows that the friction characteristics of the root-soil interface depend mainly on the roughness degree of the root surface. The results of pull-out test of a single root show that the static friction coefficients of root-soil interface of the roots of C. korshinskii and Z. xanthoxylon are 0.74±0.03 and 0.56±0.04 respectively and that the friction resistances per unit area of root-soil interface of C. korshinskii and Z. xanthoxylon are 22.94±1.15 kPa and 17.26±1.36 kPa respectively，which reflects that the former has a more significant friction resistance per unit area between root and soil.
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2018, Vol. 37 
