Studies On Mechanical Properties Of Materials Of Artemisia Ordosica

In this paper,we researched the material mechanics of the roots of Artemisia ordosica which is one of the avant-garde plant in the coal mining subsidence area of Ordos and Shenmu county.The main contents of the research included the anti-tension force characteristic,the anti-fracture force characteristic,the elastic-plastic,the constitutive behavior,the vulnerable root parts and the vulnerability by exogenic force of the straight root and lateral root branch of Artemisia Ordosica.These results will elucidate the mechanisms of Artemisia ordosica root reinforcement and they can provide some theoretical basis for the selection of plant species for local vegetation construction.The results of the research are as follows:(1)The anti-tension force and the anti-fracture force of straight roots and lateral root branch of artemisia ordosica were positively correlated with the diameter of roots with a power function and both of the anti-tension strength and the anti-fracture strength were negatively correlated with the root diameter with a power function.For the straight roots,the anti-tension force increased from 15.11 N to 99.39 N,the anti-tension strength decreased from 13.40 MPa to 5.56 MPa,the anti-fracture force increased from 10.08 N to 74.77 N,the anti-fracture strength decreased from 8.33 MPa to 4.05 MPa with the increase of the root diameter;For lateral root branch,the anti-tension force increased from 9.48 N to 72.30 N,the anti-tension strength decreased from 6.81 MPa to 3.85 Mpa,the anti-fracture force increased from 9.58 N to 76.11 N,the anti-fracture strength decreased from 8.40 MPa to 4.12 MPa with the increase of the root diameter.(2)The F~s curves of straight roots and lateral root branch of artemisia ordosica under the two forms of axial force and radial force showed the elastoplastic characteristics.The experimental roots were all transition from elastic deformation to plastic deformation in the process of testing.The stress~strain curve(?~? curve)of straight roots and lateral root branch under the axial force were mainly characterized by up-convex.The ratio of stress and strain of the elastic limit point to the ultimate stress and strain of the test roots were:(47.43%~62.44%,24.36%~33.88%),(42.86%~61.56%,26.32% ~ 42.89%).The ? ~ ? curve under the radial force were mainly characterized by down-concave.The ratio of stress and strain of the elastic limit point to the ultimate stress and strain of the test roots were:(15.94%~24.78%?11.43%~19.22%),(16.67%~19.85%?12.04%~19.72%).(3)For the test root of each part of the adjacent root segment in each diameter level,the anti-tension force,anti-fracture force and average root diameter distribution were: adjacent upper straight roots>lateral root branch>adjacent subordinate straight roots.The average anti-tension strength and anti-fracture strength were: adjacent subordinate straight roots>lateral root branch>adjacent upper straight roots.The ability to resist external force of lateral root branch was better than adjacent subordinate straight roots and weaker than adjacent upper straight roots.But the strength still negatively correlated with the root diameter.(4)The vulnerability of straight roots and lateral root branch load types were radial force.For the straight roots,the average anti-fracture strength were 68.83%~82.69% of anti-tension strength.For the lateral root branch,the average anti-fracture strength were 60.75%~94.04% of anti-tension strength.