青藏高原东北部黄土区灌木柠条锦鸡儿根—土界面剪切特性
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TU43

基金项目:

国家自然基金青年项目“青藏高原东北部黄土区垂直根型灌木根系锚固机理研究”(42002283);国家自然科学基金项目(42062019);第二次青藏高原综合科学考察研究项目(2019QZKK0905)。


Shear Characteristics of Root-Soil Interface of Caragana Korshinskii in Loess Area of Northeastern Qinghai-Tibet Plateau
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    摘要:

    [目的] 分析不同因素对根—土界面抗剪强度指标和抗剪强度的影响,为深入探讨青藏高原东北部黄土区灌木根系固土护坡机制提供理论依据。[方法] 以区内优势灌木植物柠条锦鸡儿(Caragana korshinskii)为研究对象,通过根—土界面直剪试验,分析根径级别为2.20±1.00~32.00±1.80 mm以及土体含水量、干密度和含盐量分别为6.00%~22.00%,1.20~1.60 g/cm3,0.59%~2.50%的条件下,各因素对柠条锦鸡儿根—土界面抗剪强度指标和抗剪强度的影响规律。[结果] 在其他影响因素恒定的情况下,根径对根—土界面抗剪强度指标和抗剪强度无显著影响(p>0.05)。随着土体含水量由6.00%增大到22.00%,根—土界面黏聚力呈先增大后减小的趋势,当土体含水量达到14.00%时黏聚力达到峰值6.74 kPa;根—土界面摩擦角由21.40°降低至15.75°,呈线性函数降低趋势;根—土界面抗剪强度呈线性函数降低趋势。随着土体干密度由1.20 g/cm3增长至1.60 g/cm3,根—土界面黏聚力由5.70 kPa增大至6.85 kPa,呈指数函数增长趋势;根—土界面摩擦角由20.67°增大至21.67°,呈线性函数增长趋势;根—土界面抗剪强度呈线性函数增大趋势。随着土体含盐量由0.59%增大至2.50%,根—土界面黏聚力由6.71 kPa增大至7.31 kPa,呈线性函数增长趋势;根—土界面摩擦角无显著变化(p>0.05);根—土界面抗剪强度呈线性函数增长趋势。通过灰色关联分析可知,土体干密度对根—土界面黏聚力、摩擦角和抗剪强度的影响程度最大。[结论] 土体含水量、干密度和含盐量均能够影响根—土界面抗剪切特性,但影响程度存在差异;在评价植物根系对黄土斜(边)坡浅层土体的防护效果时,必须充分考虑降雨入渗对根—土界面剪切特性的影响。

    Abstract:

    [Objective] The effects of different factors on the shear strength index and shear strength of the root-soil interface were analyzed, in order to provide an understanding of the mechanism of shrub root soil fixation and slope protection in the loess region of the Northeastern Tibetan Plateau. [Methods] The dominant shrub (Caragana korshinskii) for this region was selected as the study object, and the effects of the dry density, moisture content, and salt content of soil, and of root diameter on the shear characteristics of the root-soil interface and their mechanisms were analyzed and discussed using the direct shear test (i. e., one factor was varied at a time) for root diameters of (2.20±1.00—32.00±1.80) mm and moisture contents, dry densities, and salt contents of the soil of 6.00%—22.00%, 1.20—1.60 g/cm3, and 0.59%—2.50% respectively. [Results] Root diameter had no significant effect on the shear strength indexes and shear strength of the root-soil interface (p>0.05) when other influencing factors were held constant. As soil moisture content increased from 6.00% to 22.00%, the root-soil interface cohesion initially increased and then decreased, reaching a maximum value of 6.74 kPa at a soil moisture content of 14.00%. The root-soil interface friction angle decreased linearly from 21.40° to 15.75°. The shear strength of the root-soil interface decreased linearly. As the soil dry density increased from 1.20 g/cm3 to 1.60 g/cm3, the cohesion of the root-soil interface increased exponentially from 5.70 kPa to 6.85 kPa, and the friction angle increased linearly from 20.67° to 21.67°. The shear strength of the root-soil interface increased linearly. As the soil salt content increased from 0.59% to 2.50%, the root-soil interface cohesion increased linearly from 6.71 kPa to 7.31 kPa, and the shear strength increased linearly. However, there was no significant change in the root-soil interface friction angle (p>0.05). The gray correlation analysis of these results showed that dry density had the greatest influence on the cohesion, the friction angle, and the shear strength of the root-soil interface. [Conclusion] The dry density, moisture content, and salt content of soil can all affect the shear characteristics of the root-soil interface, however, the degree of influence is different. The influence of rainfall infiltration on the shear characteristics of the root-soil interface should be fully considered when evaluating the protective effect of plant roots on the shallow soil of loess slopes.

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石川,刘亚斌,朱海丽,梁燊,薛立夫,王舒,胡夏嵩,李国荣.青藏高原东北部黄土区灌木柠条锦鸡儿根—土界面剪切特性[J].水土保持通报,2023,43(1):69-77

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  • 收稿日期:2022-05-05
  • 最后修改日期:2022-06-17
  • 在线发布日期: 2023-04-08