Study On Root-soil Mechanical Characteristics Of Four Common Arbor Root System

To explore the tree to prevent shallow slope, retaining water and soil mechanism, indoor axial tensile test of a single tensile tests were taken on the four kinds of common trees of the North China in mountainous area:Pinus tabulaeformis, birch, larch and Mongolian oak, and itssingle tensile mechanical properties were determinated; qualitative analysis of the diameter, species, distance and stretching rate and other factors were taken on the tensile strength, resistance to tension and stress-strain relations; on this basis, further quantitative analysis were taken to establish a single tensile strength of the model and describe the stress-strain relationship of empirical models. Then, Pinus tabulaeformis roots were selected as test root samples with the North China Hunting retrieve soil samples with the preparation of the root soil composite sample, using fully automated triaxial compression shear test in complex to study the complex shear characteristics.The major results were summarized as follow:(1) Level of tensile strength of four kinds of tree roots:birch> Mongolian oak> Pinus tabulaeformis> larch; four species root tensile strength was negatively correlated with the diameter gauge; in the same diameter class, root length and tensile strength was negatively correlated; the influence of stretching rate on root tensile strength is less obvious.(2) The stress-strain curve of single arbor root was a single peak curve, there was no obvious diameter reduction. Four trees in the stress-strain curves show the elastic-plastic material characteristics, but in the early stages of tensile, showed elastic material characteristics; once stress exceeds the elastic limit, root deformation rapidly went into the elastic and plastic deformation stage.(3) Introduced species, troot length as a control variable to build a comprehensive model of forest single tensile mechanical properties of four species roots, its mathematical expression for P=a(S,L)+b(S,L)/D. To some extent this model can reflect the trees of a single mechanical mechanism, a certain degree of practical significance.(4) An empirical model was established to reflect the single roots constitutive relation, and from a mathematical perspective, the theory argumentation and derivation of model were taken and its parameters were calculated out.(5) Root-soil can significantly improve the ability of soil to resist shear failure, and the effect of perpendicular to add the root is stronger than that of in the level of the root effect; the increase of confining pressure, and buried in the root segment diameter increases this strengthening effect is more obvious.