标距对垂穗披碱草根系抗拉特性影响统计研究

Impact of gauge length on the tensile mechanical indices of roots for Elymus nutans based on statistical theory

为探讨标距对植物根系抗拉特性指标分布影响,选取根径变化范围较小的草本垂穗披碱草根系为研究对象,对该植物根系开展标距为20,40和80 mm条件下单根抗拉试验,测定其根径、抗拉力等指标,并计算单根抗拉,强度、拉伸率和拉伸模量:在此基础上,以标距为控制因子,通过单因素方差分析,探讨标距对单根抗拉指标的影响,探究标距对各抗拉特性指标分布影响,并探讨标距对各指标平均值、标准差和变异系数等影响,然后采用,正态分布、对数正态分布和威布尔分布对上述指标进行分布拟合。研究结果表明,单根抗拉力、抗拉强度和拉伸率随标距增加而减少,而拉伸模量则随标距增大而增加,表现出显著性依赖于标距的特征;根径与其抗拉指标函数关系不依赖于标距;正态分布、对数正态分布及威布尔分布均可模拟垂穗披碱草根系抗拉指标分布,不同指标最优分布函数各不相同,其中根径、拉伸模量和抗拉力最优分布不依赖于标距。根径和拉伸模量最优分布函数均,为正态分布,抗拉力最优分布函数为威布尔分布,而抗拉强度和拉伸率最优分布则依赖于标距,表现在抗拉强度,最优分布函数为正态分布、威布尔分布或对数正态分布,拉伸率最优分布为对数正态分布或威布尔分布:抗拉力、抗拉强度及拉伸率平均值与标距呈负相关关系,拉伸模量平均值则与标距呈正相关性,抗拉力和拉伸率标准差与标距呈负相关性,而抗拉强度和拉伸模量标准差与标距呈正相关性:抗拉力变异系数与标距呈负相关性,而抗拉,强度和拉伸模量变异系数与标距呈正相关性。该研究结果对于进一步合理评价草本植物根系固土护坡能力和贡献提供理论参考依据,同时对于科学有效防治坡面水土流失、浅层滑坡等地质灾害具有理论指导意义和实际应用价值。

To investigate the impact of gauge length on the tensile mechanical indices of roots,Elymus nutans was selected as the tested objects due to its narrow variation in its diameter.After that,tension test was conducted on the roots with its gauge length of 20,40 and 80 mm,and meanwhile tensile resistance,tensile strength,tensile strain and tensile modulus of the roots as well as its diameter were also measured.Built on these results,one-way analysis of variance(One-way ANOVA)was conducted to investigate the impact of gauge length on the tensile mechanical indices of roots,in which gauge length was taken as the independent variable and other indices as tensile resistance,tensile strength,tensile strain and tensile modulus were taken as dependent variables.And then Normal distribution,Lognormal distribution and Weibull distribution were introduced to describe the distribution of these indices.The results show that tensile resistance,tensile strength and tensile strain exhibit a decreasing trend with gauge length decreasing,while tensile modulus exhibits an opposite trend,gauge length exerts no impact on the relation between root diameter and its tensile mechanical indices.Normal distribution,Lognormal distribution and Weibull distribution could be used to describe the distribution of the tensile mechanical indices for E.nutans.The optimal distribution for both root diameter and its tensile modulus is normal distribution,and the optimal distribution for tensile resistance is Weibull distribution,indicating that the optimal for these indices is independent on gauge length,whereas the optimal distribution for tensile strength is Normal or Weibull distribution,and the optimal distribution for tensile strain is Lognormal or Weibull distribution,indicating that the optimal distribution for the two indices(tensile strength and tensile strain)are dependent on gauge length.Negative correlations between tensile resistance,tensile strength,tensile strain,and gauge length was discovered,whereas a positive correlation between tensile modulus and gauge length was found.This finding can be used to widen and deepen the theory of slope protection by vegetation,and meanwhile this conclusion has a theoretical significance and practical value in preventing soil erosion,shallow landslide and other geological hazards in areas suffering from severe soil erosion and shallow landslides.