Effect Evaluation Of Slope Protection With Several Herbs

In recent years, infrastructure construction gets rapid development in China. Highway, railway, water conservancy and other engineering construction often needs excavating a lot of slopes. The excavation destroys vegetation seriously, then leads to soil erosion, landslide, mud-rock flow and other ecological environment problems. Although anti-washout ability is good for traditional slope projection, the economy and landscape effect are bad. Using vegetation can protect slope, and overcome the shortcoming of traditional slope protection ways. Slope protection with vegetation is a new technology which is using vegetation to preserve water and soil, to reduce slope instability and corrosion, simultaneously beautify ecological environment.This article takes Northeast Forestry University tree farm as an experimental field. According to climatic conditions of northeast area, soil conditions of highway slopes and other conditions, this text selects 5 different common herbs (Festuca rubra L., Medicago sativa L., Trrifolium repens L., Coronilla varia L., Poa pratensis L.) to plant, and observes ecology compatibility and preserving soil ability of each kind of plants, then uses mathematical method to appraise slope protection effect of each kind of plant. The main work of this article is :(1) Observing germination, growth rate, coverage, drought resistance, thermal resistance and other indexes, then takes these as important indexes for slope protection effect evaluation.(2) In the condition that it does not destroy the undisturbed soil as far as possible, using ring sampler to take soil samples which containing plant roots in site, then carries on massive direct shear tests and gets shear strength, at last, gets complex cohesive force and internal friction angle of different root-soil samples. Compare these with soil samples which not containing roots, and then evaluate presving soil ability of different herb.(3) Carrying on massive drawing tests in site, obtains the anti-drawing strength of different herb, which is an important index for effect evaluation of slope protection.(4) According to indexes, applying fuzzy comprehensive evaluation based on analytic hierarchy process to carry on comprehensive evaluation. At last, finds out the herb which is best suit for these conditions.According to experiments, it comes to elusions that Medicago sativa L. and Coronilla varia L. are the first choices for slope protection in these conditions in the text, but Medicago sativa L. is better than Coronilla varia L.; then we can choose Trrifolium repens L. as slope protection plant; the slope protection effects of Festuca rubra L. and Poa pratensis L. are worse, the most main reason is that ecology compatible ability is weak under these conditions in the text, we may consider these plants as slope protection plants in the moist area.