Mechanical Properties Of 5 Plant Roots And The Response To Soil Moisture

In this paper,used Caragana Korshinskii.Kom,Hippophae rhamnoides.Lin,Hedysarum fruticosum Turcz,Medicago sativa.L and Astragalus adsurgens.Pall as the object,through the indoor single axial stretching,cantilever beam bending test,root soil shear test and soil boundary friction test.Research 5 kinds of plant roots biomechanical characteristics of the solid soil resistance to erosion and its response to the soil moisture.To exposes the mechanical properties of five kinds of plant roots soil fixation and interspecific differences and biomechanical characteristics of common laws.To provide the basic data for the selection and disposition of plant species in arid and semi-arid.areasthe results as follows:(1)When 3 kinds of plant roots in the range of 0?6mm,with theIncrease in diameter,single ultimate tensile and bending resistances is increase with power function.Ultimate tensile strength and flexural strength is decline with power function.When the diameter of the 3 plants represents the root diameter class,the limit tensile resistance's size of the order of single root:Hippophae rhamnoides.Linn(6 1.09N)>Caragana Korshinskii.Kom(56.91 N)>Medicago sativa.L(26.42N),the ultimate tensile strength of single root size order:Caragana Korshinskii.Kom(126.12MPa)>Hippophae rhamnoides.Linn(79.1 7MPa)>Medicago sativa.L(68.51 MPa);3 kinds of flexural strength of single root of plant size order:Caragana Korshinskii.Kom(0.55N)>Medicago sativa.L(0.38N)>Hippophae rhamnoides.Linn(0.16N),3 kinds of bending strength of single root of plant size order:Caragana Korshinskii.Kom(22.09MPa)>Medicago sativa.L(17.36MPa)>Hippophae rhamnoides.Linn(4.77MPa).When the soil moisture content is between 4.5%?24.5%,with the increase of soil moisture content,the ultimate tensile strength and bending strength is decrease progressively.(2)Under test conditions of root soil composite,shear strength and cohesion of 5 plant roots composites is different with plain soil and it's value respectively were biger than plain soil,Astragalus adsurgens.Pall is greater than the other 4 kinds of plants.Five kinds of plant root complex soil shear strength value is:Astragalus adsurgens.Pall(20.84KPa)?Caragana Korshinskii.Kom(17.41KPa)?Hippophae rhamnoides.Linn(17.60KPa)?Medicago sativa.L(14.56KPa)and Hedysarum fruticosum Turczl6.23(KPa);Cohesive force of value is:Astragalus adsurgens Pall(12.22KPa)?Caragana Korshinskii.Kom(11.63KPa)?Hedysarum fruticosum.Turcz(11.56KPa)?Medicago sativa.L(11.05 KPa)and Hippophae rhamnoides.Linn(10.65KPa).When the soil moisture content is between 4.5%?24.5%,with the increase of soil moisture content,5 kinds of plant roots and soil complex shear strength and cohesive force of all showed a trend of decrease after the first increasencrease of soil moisture content and soil to root complex and internal friction angle of soil has no influence.(3)Under natural habitat,the shallow soil layer of root system distribution around 0.8 m.The friction coefficient of size order:.Hippophae rhamnoides.Linn(0.7707)>Hedysarum fruticosum.Turcz(0.7629)>Astragalus adsurgens.Pall(0.159)and Caragana Korshinskii Kom(0.7157)>Medicago sativa.L(0.6239)>plain soil(0.5337).The coefficient of friction ratio of size order:Hippophae rhamnoides Linnl.44>Hedysarum fruticosum.Turcz(1.43)>Astragalus adsurgens.Pall(1.34)and Caragana Korshinskii.Kom(1.34)>Medicago sativa.L(1.17).When the soil moisture content is between 4.5%?24.5%,with the increase of soil moisture content,5 kinds of plant roots and soil interface and plain soil angle of internal friction of the interface is decreasing trend;5 kinds of plant root soil interface friction is decreasing trend;plain soil interface friction coefficient is after the first increases and trend of decrease.(4)When 5 kinds of plant roots in the range of 0?6mm,with thelncrease in diameter,the mean resistance force of 5 kinds of plant roots and soil interface is increase;and the shear strength is decrease with power function.On behalf of the root diameter class,5 kinds of drawing an average shear strength of single root of plant size order:Hippophae rhamnoides.Linn(112.11KPa)>Medicago sativa.L(97.65KPa)>Astragalus adsurgens.Pall(95.50KPa)>Caragana Korshinskii.Kom(89.81KPa)>Hedysarum fruticosum.Turcz(69.38KPa).When the soil moisture content is between 4.5%?24.5%,with the increase of soil moisture content,5 kinds of plant roots and soil boundary drawing shear strength is first increases and then decreases;When soil moisture content of 10.86%,the drawing shear strength have the maximum value.