Research Of Capability Of Soil Conservation Of Herb Plant Root Used In Cutted Slope Of Highway

Plant protection technique is an advanced technique of the slope protection, involving ecological restoration and environmental protection and other functions, it has been widely used in the field of engineering construction. Plant protection technique involve in ecology, landscape science, biology, engineering and aesthetics, etc. fields, and it has very close links with related disciplines. From the field of engineering, we can research construction technology of plant slope to make protection and protection scheme according to the different situation of a slope. From the field of ecology to research the interaction of plant roots and soil, the plants and the environment interaction, to illustrate the mechanism of plant slope protection, to compare different plant ability of the differences slope protection. The previous study focused on the plant roots of the trees and shrub, much more than the slope protection ability of the herbaceous plants research.The passage surveyed the slope protection of Guangnan highway, mainly studied three kinds of main herb plants are used in slope protection about distribution characteristics of root system, tensile ability of root and shear strength of soil root composites, discussed and analyzed the protection mechanism the slope and the plant protection capability. The main conclusions and results are as following:(1) The root system distribution of three kinds of protective plant(bermudagrass, ryegrass, tall fescue is shallow. Root content decreased with the increase of soil depth, the relationship between two exponential correlation. Three kinds of plant root in most distribution within the depth of 0-8cm, the total root biomass accounted for more than 94%, while only a few root exists in the soil more than 8cm depth. Root content in depth 0～10cm of three kinds of plants showed:tall fescue> ryegrass> bermudagrass. In the range of root system distribution, slope is considered as a kind of composite material composed of soil and roots. Herbs roots go through into the soil, just as "reinforced", can greatly enhance the stability of the slope and erosion resistance.(2)Three kinds of plant roots in less than lmm in diameter have great tensile strength as bermudagrass, ryegrass and tall fescue maximum tensile strength can reach to 44.840MPa,101.859MPa and 174.628MPa. It seems that different plant has different tensile ability. Compared with three species, single root tensile ability of three kinds of plants shows an obvious difference:tall fescue> ryegrass> bermudagrass.(3)Roots of three kinds of plants in less than lmm in diameter single maximum tensile forces increased with the diameter increasing, while the tensile strength with the diameter decreasing.Root tensile ability of bermudagrass, ryegrass and tall fescue and root diameter is an exponential function, which make plant root maximum tensile strength increase with the increase of root diameter, while the tensile strength decrease with the increase of diameter.(4)Soil shearing strength which content roots improved obviously than soil without roots, and shear strength increased with the increase of root contentCompared to the soil without root, and 1 times, and 1.25 times, and 1.5 times, and 1.75 times, and 2 times the measured root density conditions, the cohesion of bermudagrass increased from 14.57KPa to 17.01KPa, and the angle of internal friction from 28.22° to 30.11°, and the cohesive force of tall fescue increased from 17.31KPa to 21.34KPa, the internal friction angle from 28.59° to 30.25°, cohesion of ryegrass increased from 19.24KPa to 26.81KPa, internal friction angle from 29.54° to 31.98°.The range of the cohesive force is greater than the angle of internal friction。 The increase in root content ratio under the same conditions, increase of the cohesive force is greater than the internal friction angle increase.The three species (bermudagrass, tall fescue, ryegrass can improve the soil anti shear ability and enhance a significant cause of slope stability.The reason is the incorporation of the root and root soil composite forming a composite materials, greatly enhance its cohesion. Compared with three species of bermudagrass, ryegrass and tall fescue, Under the same conditions, the cohesion of soil increased, ryegrass>tall fescue> bermudagrass, namely three kinds of plants in the shear capacity of soil:ryegrass> tall fescue> bermudagrass.Research about slope plant protection of Guangnan highway results that herb has outstanding ability in maintaining the stability of slope. Root of herbaceous plants were decreased with the depth and for the tensile strength of single root, tall fescue is better than that of ryegrass than bermudagrass, and for containing the root soil, its shear strength is higher than that of tall fescue and ryegrass,and tall fescue is better than that of bermudagrass.