STATISTICS OF MECHANICAL CHARACTERISTICS OF FIVE HERB ROOTS STANDING IN HENAN REGION OF QINGHAI PROVINCE

To appropriately evaluate the mechanical behavior of herb roots, we select five types of indigenous herbs in Henan county of Qinghai province as the tested objectives. They are Oxytropis ochrocephala, Poa annua, Stipapurpure, Carex moorcroftii, and Kobresia humilis. Tensile tests are conducted to the roots of these selected species to obtain their tensile resistance and tensile strength. Based on these results, statistical models are adapted to qualitatively analyze the distribution patterns of the obtained values. The models include Weibull model, Gamma model, Poisson model, Rayleigh model, and Normal model. Then Kolmogorov-skmirov tests are used to quantitatively investigate the optimal distribution functions. The results show that for the five types of statistical models, Poisson model is poor for describing the distribution pattern of these values, while Weibull and Gamma distributions are excellent at describing the distribution patterns. Moreover, the optimal distribution model for root diameter is Gamma function. The optimal distribution model for tensile resistance and tensile strength of E.nutans and C.moorcroftii is Weibull model. The optimal distribution models for K.humilis tensile resistance and tensile strength for K.humilis Weibull and Gamma distributions, respectively. The optimal distribution models for tensile resistance and tensile strength of O.ochrocephala and P.annua is Gamma and Weibull distributions respectively. The results of this study play an important role in accurately estimating the mechanical behavior of herb roots.