Study On Physical Mechanism Of Interface Between Vegetation Root And Loess Soils In Ecology Slope Protection

Because there are a lot of the natural defects on traditional slope protection engineering such as easy to aging, high maintenance costs and poor sustainability, adopting the green vegetation for slope protection is being taken into account by more and more countries.The effect of plant roots for slope protection is the hot issues of interdisciplinary study,which attracted widespread attention in recent years.It is a new technology using the principle of vegetation contain water to steady slope also beautify the environment, involves rock engineering,ecology,botany, plant mechanics,mathematics and so on.As a new technology of slope protecting, plant roots protecting technology becomes the trend of defending and represents the trend of slope protecting.Based on the research bulk of domestic and foreign documentation about ecological protection and plant roots mechanics, in view of the current domestic vegetation mechanical effects of slope protecting, this paper select the roots of perennial ryegrass which from a length of the Hubei Wu(Wuhan)-Huang(Huangpi) expressway in Ezhou as practical background to make a series of discussions and research.The main achievements are as follows:(1) Based on the analysis and summary of the ecological slope protection,through a lot of indoor single tension and direct shear tests,this paper established the regression equation between tensile strength and the root diameter, tensile strength and the root diameter, and explore the effect of the distribution of plant root density, soil water content on soil shear strength. The results showed that: the plant roots can significantly raise the soil shear strength; as the level of moisture content increases, the shear strength of the soil and soil roots system complex will decline; under the same level of moisture content, as the root density is increasing, and cohesion of the soil roots system complex will continue to increase, and the increment of internal friction angle is not obvious. In addition,different distribution methods in root has different impact on the shear strength of the complex. (2) The result of the finite element analysis shows that the role of the grass plant roots can reduce the stress level of shallow soil, that can change the stress-strain state of the shallow soil;and the grass roots increase the cohesion of the shallow soil which is beneficial to the edge slope stability but not obvious effect to the depth soil.