The Anti-fracture Mechanical Characteristics Of Four Kinds Of Lateral-Root Branches

The paper simulate a kind of status that is the roots of crack is broken because of resisting radial force when the soil take place diaplacement, and to study on the anti-fracture mechanical chrarcteristics of four plants. The four plant species are the vegetation species of Caragana korshinskii, Salix psammophila, Hippophae rhamnides and Artemisia sphaerocephala. For the four plant species, the roots are selected with vitality, and the corresponding plant age of 3-4 year old.The anti-fracture forces of lateral-root branches of four plant species are measured with the self made fixture and the instrument of TY 8000. The results are as follows:(1)Within the scope of the 1 to 4 mm diameter, the four plants roots is separated timely, separated after 6 days, separated after 13 days, and separated after 20 days. Used TTC to deal plant roots, the root vigor has a trend of lower with the time increase.(2)Under the radial force about lateral-root branches of four plants, the ratios of lateral-root branches break numbers and effective test roots is above 87%, that is to say, the resistance of lateral-root branches is less than its upper and lower straight roots. The average diameters of lateral-root branches about four plants are greater than adjacent upper straight roots, but the ratios of anti-fracture strength of lateral-root branches and anti-fracture strength of adjacent upper straight roots are 15.2% for C. korshinskii,74.1% for S. psammophila,48.5% for H. rhamnides and 41.8% for A. sphaerocephala. For the four plants, the anti-fracture force and the diameter are positively correlated with power function, and the anti-fracture strength and diameter are negatively correlated with a power function. The anti-fracture strength of lateral-root branches is lesser than the anti-fracture strength of adjacent upper straight. The anti-fracture strength between lateral-root branches and adjacent upper straight roots for the four species follow the sequence of C. korshinskii>S. psammophila> H. rhamnides> A. sphaerphala.(3) In exuberant growing period and the early growing period, the anti-fracture force of C. korshinskii, S. psammophila and H. rhamnides lateral root branch have significant diffrernce, the anti-fracture force of A. sphaerphala has no significant diffrernce. In exuberant growing period and the early growing period, the anti-fracture strength of C. korshinskii have significant diffrernce, the anti-fracture strength of H. rhamnides and A. sphaerphala lateral root branch has no significant diffrernce. Under different loading rates, the anti-fracture force and the anti-fracture strength of C. korshinskii, S. psammop hila, H. rhamnides, A. sphaerphala follow the sequence of 860mm/min>500mm/min>2 OOmm/min>10mm/min. The lateral root branch segment loss water when the soil moisture content is 0, The lateral root branch segment absorb water when the soil moisture content is 7.8%、15.9%、23.8%, The anti-fracture force and the anti-fracture strength of four plants lateral root branch is a trend of lower with the increase of soil moisture content.