A single root ultimate tensile test and a root soil interface pull-out friction test were conducted using a TY-8000 tensile machine and the root system of Hippophae rhamnoides, a pioneer shrub for soil and water conservation in the arid and semi-arid areas of Inner Mongolia to investigate the effect of mowing measures on the mechanical properties of roots. The effect of mowing on the soil fixation mechanical properties of Hippophae rhamnoides root system was analyzed. The results showed that the ultimate anti-tension and resistance tensile force of a single root were positively correlated with the diameter as a power function under the conditions of mowing and non-mowing when the measured root diameter was 0-5.0 mm. The ultimate tensile strength of a single root and the tensile shear strength of the root soil interface were negatively correlated with the diameter as a power function. In the representative root diameter class of Hippophae rhamnoides ranging from 0.5 to 1.5 mm, the average ultimate anti-tension of a single root in mowing was 31% higher than that in non-mowing. The average ultimate tensile strength of a single root increased by 37% and the average pull-out shear strength increased by 30%. It is indicated that the diameter has an impact on the strength of tensile and shear of the Hippophae rhamnoides root system, and the properties of tensile and shear have been improved after the mowing treatment.
表 3 平茬和未平茬沙棘不同径级的单根抗阻拉力Table 3 Resistance tension of single root of Hippophae rhamnoides in different diameter classes between mowing and no mowing
表 1 不同径级的沙棘单根极限抗拉力Table 1 Ultimate anti-tension of single Hippophae rhamnoides root under different diameter classes
表 2 平茬和未平茬沙棘不同径级的单根极限抗拉强度Table 2 Ultimate tensile strength of single root of Hippophae rhamnoides in different diameter classes between mowing and no mowing
图1 沙棘单根极限抗拉力与直径关系Fig.1 Ultimate anti-tension of a single Hippophae rhamnoides root with diameter
图2 平茬和未平茬沙棘单根极限抗拉强度与直径关系Fig.2 Ultimate tensile resistance of single Hippophae rhamnoides root with diameter between mowing and no mowing
图3 平茬和未平茬沙棘单根抗阻拉力与根径的关系Fig.3 Resistance tension of single Hippophae rhamnoides root with diameter between mowing and no mowing
图4 平茬和未平茬沙棘单根拉拔抗剪强度均值与根径关系Fig.4 Pull-out shear strength of single Hippophae rhamnoides root with diameter between mowing and no mowing
表 4 平茬和未平茬沙棘不同径级的单根拉拔抗剪强度Table 4 The difference of shear strength of single root of Hippophae rhamnoides in different diameter classes between mowing and no mowing