Study On Effect Of Vetiveria Zizanioides Root System On Stability Of Slope In Southwest China

In recent years,with the progress of the society and the enhancement of people's a wareness of environmental protection,the plant slope protection technology has been used more and more in slope projects.Scholars at home and abroad have carried out many researches on the slope protection of plant roots and have obtained many valuable research results.However,the theoretical research of plant slope protection is still far behind the practice.Many studies have shown that the existence of plant roots can effectively improve the shear strength of soils.However,most existing researches focus on the effect of root strength and root strength on soil strength,and on the distribution of root effect on root soil composite research literature is less than.Therefore,it is very necessary to carry out relevant research on the effect of root distribution of vetiver on the root-soil complexes.Based on the existing researches,this paper conducts experimental and theoretical research on plant slopes and explores the effects of vetiver roots on the root-soil complexes in slopes in Southwest China.In this paper,a series of conventional physical performance tests,numerical simulations,and direct shear experiments were conducted to study the effect of vetiver root system on the shear strength of root composites under different distribution patterns and different spatial distribution angles.And the effect of vetiver root system on the impact resistance of soil Was studied through the original soil erosion test.The main contents of the research work in this paper and the innovative results obtained are as follows:1.Study on direct shear test of vetiver root complexThrough direct shear tests on vetiver root and soil composites under different distribution densities,different root system spatial distribution angles and different moisture contents,the following conclusions were obtained:(1)The fitting results of the shear test data verified once again that the shear strength of vetiver root complex conforms to the Coulomb strength theory.With the increase of load intensity,the shear strength of vetiver root and soil composites showed an increasing trend.The root system of vetiver can significantly improve the shear strength of soil.And the root system of vetiver changed the shear strength of the composite by changing the internal friction angle and the cohesion of the root-soil complex,and improved the stability of the slope soil.(2)It Was found through experiments that the distribution densities of different vetiver root systems have different effects on the shear strength of root-soil complexes.H1(10 group)Shear strength> H2(5:5 group)Shear Strength > H3(2:2:2:2:2 group)Shear Strength> Wa(rootless soil)Shear Strength.The test results show that under certain other conditions,the greater the root distribution density,the greater the internal friction angle and cohesion of the root-soil complex,and the greater the shear strength of the root-soil complex.(3)The study found that the spatial distribution of different vetiver roots had different effects on the shear strength of root-soil complexes.Hc(Half-vertical half-inclined 45° distribution)Shear strength> Hb(full tilt 45° distribution)Shear strength> Ha(full vertical distribution)Shear strength> Wa(rootless soil)Shear strength.Studies have shown that under the same conditions,with the change of the spatial distribution of roots,the internal friction angle,cohesion and shear strength of the root-soil complexes also changed.The spatial distribution of the roots has a significant effect on the cohesion of the root-soil complex,and has a relatively small effect on the internal friction angle of the root-soil complex.(4)The test results showed that under certain conditions such as the density of the sample,root diameter,root coefficient,root distribution density,root distribution angle,etc.with the increase of moisture content,the shear strength increases first and then decreases its root soil complex.This is in agreement with the results of previous studies.2.The numerical analysis of the effect of vetiver grass roots reinforcement(1)The existence of the root system of vetiver obviously improves the safety factor of the slope,which is beneficial to the stability of slope soil.The distribution density of vetiver root system in slopes is different,and the degree of influence on the slope safety factor is also different.The safety factor of the slope is the highest when the root system is H1(10 group).This result and the results of the different root distribution density in Chapter 4 have the same effect on the shear strength of slope soil.(2)The slope stability coefficient of different vetiver roots in spatial distribution is different.In several distribution methods,the root distribution of vetiver grass is half vertical and half inclined 45°,and the slope safety factor is the largest,which is most conducive to slope stability.3.Anti-erosion experimental studyThe test found that the impact resistance of vetiver root-soil complex is greater than that of unrooted soil in the same soil layer.The impact resistance index of vetiver root-soil complex is 2.24 times that of unrooted soil in the same soil layer,and the test results show that the presence of vetiver root system significantly improves the slope-resistance of the soil.