Study On The Anti-Fracture Mechanical Properties Of 4 Kinds Of Single Roots

The root Interspersed with growing in the soil, it show mechanical properties of resistance to breakage by external forces in the radial, After the middle of the slope soil cracked, the taproot of Caragana microphylla, Hippophae rhamnoides, Salix psammophila and Artemisia sphaerocephala four kinds tree species of Soil and water conservation are used as object of this study to find the anti-fracture forces of mechanical properties, Fixed-ends broken experiment is made in this study by the TY-8000 servo type powerful machine, TY-8000 servo powerful machine be used as laboratory equipment to test both ends fixed broken. The results are as follows:Within the scope of the 1 to 6 mm diameter, Four kinds of plants taproot Anti-fracture forces has a power growing function tendency with the increase of root diameter, Anti-fracture strength has a power decreasing function with the increase of the root diameter; there are significantly difference of the average Anti-fracture forces, Anti-fracture strength of taproot of four kinds plant species under significant level a 0.05. With the diameter increasing, the average Anti-fracture forces of four kinds of plants taproot(Caragana microphylla, Salix psammophila, Hippophae rhamnoides and Artemisia sphaerocephala) increase from 79N,32N,12N,8N to corresponding to 1119N,41 ON,141N,100N, respectively.while the average Anti-fracture strength of four kinds of plants taproot(Caragana microphylla, Salix psammophila, Hippophae rhamnoides and Artemisia sphaerocephala) increase from 62Mpa,25Mpa,8Mpa,6Mpa to corresponding to 43Mpa,15Mpa,6Mpa,4Mpa, respectively.Under different loading rates, There were significant differences of the taproot of four kinds of plants and the sorting are loading rate is 860 mm/min> the loading rate of 500 mm/min> loading rates of 200 mm/min> loading rates of 10 mm/min; With the increase of soil moisture content, The average Anti-fracture forces and Anti-fracture strength of taproot of four kinds plants all have a power decreasing function;The same conditions, The average Anti-fracture forces and Anti-fracture strength of taproot of Salix psammophila, Hippophae rhamnoides and Artemisia sphaerocephala are growing early <strong period, contrary Caragana microphylla.Within the scope of the 1 to 4 mm diameter, the changing process of constitutive-curve of four plants can be divided into slow growth period of bending force, bending force of rapid growth period and the last period of root fracture. There are no regularity between the grade for flexural strength of four kinds of plants, but interspecific differences as Caragana microphylla (15-19 mm)> Salix psammophila (11-15 mm)> Hippophae rhamnoides (8-12 mm)> Artemisia sphaerocephala (6-10 mm).The fracture study of four plants under cyclic load and noload showed that: Deformation characteristics of the four species is mainly elastic-plastic deformation,pure elastic deformation supplemented entire deformation process; the plastic limits of deformation rate for Caragana microphylla is 19 percent to 24 percent, Salix psammophila is 12 percent to 23 percent, Hippophae rhamnoides is 5 percent to 8 percent Artemisia sphaerocephala is 3 percent to 6 percent.