| Plants are difficult to survive in unstable loess slope engineering wound surface.Plant growth and reproduction will be severely hit.The effect of reducing slope erosion and instability will be gradually weakened,thus exacerbating soil erosion.Therefore,it is very urgent to quickly restore the ecological environment of the loess slope engineering wound surface and realize the protection of the plant community on the slope.In this paper,the effects of organic materials on the water sensitivity characteristics of loess are studied by laboratory experiments.Based on the requirements of plant selection on loess slopes,the plant communities for ecological restoration in the loess area of northern Shaanxi are constructed,and the direct shear test of the root-soil complex is carried out to illustrate the role of soil consolidation.Then the organic material-plant community ecological restoration mechanism is summarized into soil theory and slope protection mechanism,and the organic material-plant community ecological restoration technology process is proposed,including three-dimensional vegetation net reinforced turf construction technology and three-dimensional vegetation net reinforced turf transplantation technology.Finally,through artificial simulated rainfall test,organic material solidification slope protection and three-dimensional vegetation net reinforced turf slope protection on soil erosion characteristics,surface displacement,slope runoff and sediment yield,and slope rainwater infiltration are analysed.The mode of action at different stages of plant community ecological restoration techniques are explained.The main research results are as follows:(1)With the increase of organic materials,the disintegration speed and the disintegration form of the reinforced loess are different,the disintegration coefficient is gradually reduced,and the disintegration products MWD and GMD are gradually increased.When the organic material content is 16% or more,the test does not collapse at all.Compared with plain soil,the permeability coefficient of reinforced loess is significantly reduced under certain conditions of curing age,and the soil permeability coefficient decreases with the increase of organic material content,and the impermeability is continuously improved.With the increase of curing age,the permeability coefficient of the reinforced loess gradually decreases with a certain amount of fertilizer.Compared with plain soil,the shear strength of the reinforced loess is obviously improved under the condition of a certain amount of addition.Comprehensive comparison of the respective dosages,when the organic material content is 18% or more,can effectively exert the curing effect.The cohesive force and internal friction angle of the reinforced loess increased with the increase of the curing age.(2)The organic material does not react with the soil to produce a new crystalline substance,and the organic material does not act as a chemical reactant;after the organic material is incorporated,the volume of the soil is generally reduced,and the influence on the small pores and the medium pores is large,The pore diameter and volume are generally reduced,and the small pore volume is generally increased.With the increase of the amount of organic materials,the grain boundaries of soil samples are more unclear,more encrypted,and the number,size and uniformity of agglomerates are Gradually increasing,the three-dimensional network is irregularly connected between the particles,which makes the water stability and strength of the soil increase,the permeability decreases,and the desensitization effect of the organic material on the loess is obvious.(3)Organic materials-The soil science theory of plant community ecological restoration shows that plants can reduce soil bulk density,improve soil porosity,and improve soil aeration and water permeability.Plants can quickly accommodate precipitation and timely infiltration,with a good water source effect.The slope protection mechanism of organic material-plant community ecological restoration is as follows: the reinforced anchoring function of the plant community and rainfall interception,weakening the erosion,reducing the deep pore water pressure of the slope and inhibiting the surface runoff function.Organic materials-plant community ecological restoration technology using three-dimensional vegetation net reinforced turf transplant slope protection combined with organic materials,mainly divided into three-dimensional vegetation net reinforced turf construction technology and three-dimensional vegetation net reinforced turf transplantation technology.(4)Organic materials can inhibit the generation and development of rills on the slope of loess slopes,reduce the extent of erosion of slopes by runoff,and enhance the stability of slope soils.After incorporation of organic materials,the infiltration ability of slope soils significantly lower,there will be a phenomenon that the total amount of runoff is greater than the exposed slope.At the same time,the hardening surface of the organic material is hard and smooth,the roughness is reduced,the runoff resistance is weakened,and there is basically no gully erosion,and the sediment yield is significantly lower than that of the exposed slope;the organic material can slow down the water infiltration rate and reduce Small amount of infiltration,enhance soil impermeability.(5)The anti-erosion ability of the ecological restoration slope is obviously improved compared with the bare slope,which shows that there is almost no slope erosion development,and the slope has no obvious deformation and instability.The ecological restoration slope improves the soil infiltration rate by improving the physical and chemical properties of the soil and increasing the roughness of the slope.The infiltration rate of the ecological restoration slope is smaller than that of the exposed slope,thus reducing the sediment concentration.Compared with bare slopes,the water infiltration rate and infiltration amount of ecological restoration slopes increased significantly,and the infiltration time was significantly advanced,indicating that the ecological restoration slope intercepted runoff,and the ability to store water was stronger than that of bare slopes. |
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