青藏高原两种典型植物根系抗拉特性与其微观结构的关系

Relationship Between Tensile Properties and Microstructure of Two Typical Plant Roots in the Qinghai-Tibet Plateau

为研究青藏高原东部边坡、路堑两种常见的护坡植物根系抗拉特性及其与根系微观结构的关系,对灌木植物柠条锦鸡儿和草本植物草地早熟禾根系进行了室内单根拉伸试验和根系断面电镜扫描试验。试验结果显示:两种植物根系抗拉力随着根径的增大呈幂函数增大;根系抗拉强度随根径的增大呈幂函数或指数函数减小。草地早熟禾根系平均抗拉力在标距为40mm时达到最大值;柠条锦鸡儿根系平均抗拉力在标距为80mm时达到最大值;当拉伸速率为3mm/min时,两种植物根系抗拉力和抗拉强度最大,两种植物在拉伸速率为5mm/min和10mm/min时,其抗拉强度变化不明显。两种植物单根拉伸应力—应变曲线呈单峰曲线,无明显的颈缩现象,具有弹塑性材料特点,且根径较小的草本植物草地早熟禾根系表现出具有较高的抗拉强度、较大的延伸性能。根系断面显微结构中,柠条锦鸡儿和草地早熟禾根系横断面的管孔孔径随着拉伸速率的增大逐渐减小,减小幅度依次为91.25%,45.41%,表皮破坏程度也相应的减弱。根系的拉伸横断面表皮撕裂程度及表皮延长程度随拉伸速率、拉伸标距的增大而减小。

In order to study relationship between the tensile properties of root system and the root microstructure of two common slope protection vegetations in the slope and road cutting of eastern Qinghai-Tibetan Plateau,the single root tensile test and SEM test of Caragana korshinskii Kom.and Poa pratensis L.were carried out to study the tensile properties of root system and its relationship with the microstructure.The results showed that the root tensile resistances of the two plants increase exponentially with the increase of diameter;the tensile strength of roots decreases with the increase follows the diameter as a power function or an exponential function.The average tensile resistance of Poa pratensis L.root reaches its maximum at the 40 mm gauge length,while the average tensile resistance of Caragana korshinskii Kom.root reaches its maximum when the gauge length distance is 80 mm;at different stretching rates,the tensile resistance and tensile strength of two kinds of plant roots reach the maximum under the stretching rate of 3 mm/min,and the tensile strength of two plants under the stretching rate of 5 mm/min and 10 mm/min does not change significantly.The stress-strain curve of two plants shows the single-peak curve without obvious necking phenomenon,and it has the characteristics of elastic-plastic material.The herbs Poa pratensis L.roots with smaller diameter possesses higher tensile strength and greater extension properties.By observing the microscopic structure,the pore diameter of the cross sections of Caragana korshinskii Kom.and Poa pratensis L.decrease with the increase of the stretching rate,the decrease ranges are 91.25%and 45.41%,respectively,and the extent of epidermal destruction accordingly decreases.The extent of epidermal tear and the extent of epidermal elongation in tensile cross section decrease with the increase of stretching rate and elongation.