Research On The Distribution And Tensile Properties Of The Root System Of The Slope Herbaceous Plant In Puhong Road, Dujiangyan City

In this paper, we apply the multi-disciplinary theory of soil and water conservation science, botany, ecology and engineering mechanics, select 6 species of herbaceous plants from having completed PuHong road slope, systematic study on the extinction coefficient, vertical distribution characteristics and tensile properties of root system. Then, combining with the slope protection of the status quo of Puhong Road, we explore the benefits of soil and water conservation, slope and soil protection of six kinds of herbs for PuHong road, which providing the theoretical support and reference for the study of herbaceous slope protection in mountainous road.1. Distribution Characteristics of Root SystemDue to the different species of 6 species of herbaceous plants in PuHong road slope, average root quantity of plants and vertical distribution of root weight are significantly different. Here is the distribution regular of root number, Imperata cylindrica (Linn.) Beauv> Lolium perenne L> Iris tectorum Maxim> Juncus effusus L> Polystichum Roth> Equisetum arvense L; The root weight distribution in surface soil is Lolium perenne L> Iris tectorum Maxim> Juncus effusus L> Imperata cylindrica (Linn.) Beauv> Equisetum arvense L> Polystichum Roth. Comprehensive analysis of the root number and root weight distribution rule, we come to a conclusion that Lolium perenne L, Imperata cylindrica (Linn.) Beauv, Iris tectorum Maxim and Juncus effusus L, have the ability of absorbing nutrients, soi and water conservation for the slope in the surface soil.2. Characteristics of Root System Extinction CoefficientRoot system extinction coefficient can reflect the percentage of distribution in different soil layers. The root extinction coefficient is Lolium perenne L> Iris tectorum Maxim> Imperata cylindrica (Linn.) Beauv> Juncus effusus L> Polystichum Roth> Equisetum arvense L when the plant root weight is accumulated more than 90%; it is Lolium perenne L> Iris tectorum Maxim> Imperata cylindrica (Linn.) Beauv> Juncus effusus L> Equisetum arvense L> Polystichum Roth when more than 50%. Comprehensive analysis of the root system distribution feature, we conclude that the root system of Lolium perenne L, Imperata cylindrica (Linn.) Beauv and Iris tectorum Maxim are not only on the slope surface moisture and nutrient absorption, but also has important significance for soil and water conservation and slope protection in the deep soil of slope.3. Analysis of Density,Diameter and Tensile Strength of Single RootThe relationship between diameter and tensile strength of single root in 6 kinds of plants is a power function. With the increase of single root diameter, single root tensile strength decreased gradually, the function model is Tr=aDb, Tr is the tensile strength, D is the diameter, a and b are constant (a> 0, b< 0); The density and tensile strength of single root is a exponential function. the tensile strength increases with the increase of root density, the function model is Tr=aebp, Tr is the tensile strength, p is density, e is a natural logarithm, a and b are constant (a> 0, b> 0).When the root diameter of the plant is 0.20mm, the single root tensile strength of Lolium perenne L, Imperata cylindrica (Linn.) Beauv, and J Iris tectorum Maxim greater than Juncus effusus L and Equisetum arvense L; with the increasing of the root system, when the root diameter increase to 0.30mm, the single root tensile strength of Juncus effusus L is greater than Imperata cylindrica (Linn.) Beauv. When the single density ranges from 0.5 g/mm3 to 1 g/mm3, the single root tensile strength of Imperata cylindrica (Linn.) Beauv, Lolium perenne L and Iris tectorum Maxim is strong; with the single density increase from 1 g/mm3 to 1.5 g/mm3, the single root tensile strength of Polystichum Roth is growing strongly.4.Forecast Analysis of the Increment of Soil Shear SrengthThe shear srength increments of Lolium perenne L, Imperata cylindrica (Linn.) Beauv, and Iris tectorum Maxim are larger than the Juncus effusus L, Equisetum arvense L, Polystichum Roth in the same soil; With the increase of soil depth, the projections of soil shear srength increments of 6 kinds of plants presents the change trend which is increased firstly and then decreased. When the soil depth is 10 cm, the soil shear strength increment of each plant is the largest.Comprehensive analysis of tensile strength, distribution of root weight, and extinction coefficient of root system, Lolium perenne L, Imperata cylindrica (Linn.) Beauv and Iris tectorum Maxim can be used as optimal herb for slope and soil protection and soil and water retention in PuHong road slope.