An Experimental Study On Herb Plant Root System For Model Construction And Strength

With the development of hydropower and other infrastructure construction,people gradually transfer their focus to ecological protection.The bio-slope-engineering not only embodies the function as an engineering facility but also attracts attention due to its green and ecological characteristics.Among them,herbaceous roots are used as a bridge connecting herbs and soils.In order to establish a universal root model that can reflect the relationship between herbaceous plants and soil,this paper discusses the changing characteristics of soil carrying capacity due to the presence of roots,and uses physical experiments and theoretical derivation methods to determine the distribution patterns and laws of root systems.Based on this study,a corresponding root model was established to explore the tensile properties of plant roots and analyze the mechanical effects of roots on the soil structure.The research results can provide theoretical and design basis for slope protection slope protection project.In this experiment,representative herbaceous plants of Festuca arundinacea,Trifolium repens,L.perenne were selected as test grasses,cultivated in a potted manner,scanned and analyzed for sample roots,and a single sample was subjected to a tensile test and data of the test results.Analysis,using the limit equilibrium method for the theoretical analysis of the anti-sliding stability of the root-containing soil.The results show:(1)Within the range of root growth,all three herbaceous plants showed a feature that the root length density gradually decreased with the deepening of the soil layer.The average root length density was ranked as follows:L.perennes(0.045cm/cm~3),Trifolium repens(0.133cm/cm~3),Festuca arundinacea(0.156cm/cm~3);the number of single roots decreased with the increase of soil depth,and the total number of Festuca arundinacea per plant reached1,210.There were 732 Trifolium repens and 159 L.perennes;the total root length and total root surface area of three herbaceous plants had the same tendency as the growth depth.The total root length and total root surface area of Festuca arundinacea were the highest,respectively.It was 1080.25mm and 79.30cm~3,while the value of L.perennes was the smallest,95.28mm and 7.54cm~3,respectively.(2)Select the root diameter as the calculation index using the root scan data,,assuming that each root branch is based on the same rules,determine the root branch parameters,establish the formula for calculating the root length from the diameter of the root base,and the root of the individual plant.The total length is effectively predicted.(3)Tensile strength decreased with increasing diameter,and tensile strength of Festuca arundinacea increased.The maximum was 375 MPa;the elastic modulus of the three plant roots showed a downward trend with the increase of the root diameter.In the range of the root diameter of 0.05-0.25 mm,the average value of the elastic modulus was as follows:L.perennes>Festuca arundinacea>Trifolium pallidum;in the root system with a diameter of0.25-0.40mm,the relationship between the elastic modulus values is:Trifolium repens>L.perennes>Festuca arundinacea.The elastic modulus range of the L.perennes root system is1116.383~1686.752Mpa,the elastic modulus range of the Festuca arundinacea root system is169.28~631.93Mpa,and the elastic modulus of the Trifolium repens system is135.084~633.910Mpa.(4)It is assumed that the internal friction angle of the root-soil complex is equal to the internal friction angle of a single soil,and the presence of the root only changes the cohesion of the soil.The general equation(5-13)for increasing the shear strength of soil due to the presence of root system was deduced.The comparison between the predicted results and the actual results shows that the shear strength values of Festuca arundinacea,Trifolium repens and L.perennes are higher than those of plain soils.The multiples were:1.59 times,1.26 times,and 1.24 times.Regardless of the influence of groundwater level,assuming that the sliding soil body is a rigid body that does not deform,establish the stability equation of the shallow grass slope,and calculate the Festuca arundinacea,black,according to the formula of the shallow slope safety factor(5-13).The safety factors for wheatgrass and Trifolium repens were 2.306,1.560,and 1.029,respectively.The multiples increased compared to plain soil were:2.080 times,1.540 times,and 1.010 times.