Study On The Influence Of Different Herb Root Types On The Stability Of Shallow Slopes

With the rapid development of green construction,ecological slope protection has become the first choice of shallow slope treatment projects.Because the roots of herbaceous plants have unique mechanical and hydraulic effects,the roots directly affect the stability of shallow slope.To study the influence of different root types of herbaceous plants on the shallow stability of slopes,the Haizhou open-pit mine dump was used as the research site.Through on-site investigation,the root types of herbaceous plants were determined and the research object was selected the axial root type’s ASE.Willd、the tiller root type’s V.Philippica and the rhizome root type’s Triglochin Palustre.From the perspective of mechanical properties and hydraulic effects,this study investigates the influence of herbaceous plant roots on soil mechanical properties and permeability and uses numerical simulation software to analyze the impact of herbaceous plant roots on shallow slope stability under rainfall conditions.The main research content and conclusions are as follows:(1)From the perspective of root affecting soil mechanical properties,the effects of different types of roots on soil shear strength were studied by using picture pixel conversion method,root tensile test,direct shear test and unconfined compression test.The results showed that the three herbaceous plants were mainly distributed at depths of 0～12cm in soil.With the increase of soil depth,while the distribution parameters of the tiller-type roots showed a trend of first increasing and then decreasing with the increase of soil depth.All three types of root systems can improve the cohesion and internal friction angle of the root-soil composite to varying degrees,and the reinforcement effect of the rhizome herbaceous plants is the best within the entire reinforcement range.RAR can be used as an important parameter to predict the improvement of soil shear strength by the rhizome herbaceous plants and the axial root herbaceous plants.(2)From the perspective of the influence of roots on soil permeability,permeability tests were conducted to study the effects of different types of root distribution on soil permeability parameters.The results indicate that the three root soil complexes all improved the soil permeability to varying degrees.The order of permeability of the root-soil complex is the rhizome root > the axial root > the tiller root.With the increase of soil depth,the various infiltration characteristic parameters of the root-soil complex of the axial root type’s ASE.Willd and the rhizome root type’s Triglochin Palustre gradually decreased,while the various infiltration characteristic parameters of the root-soil complex of the tiller root type’s V.Philippica showed a trend of first increasing and then decreasing.RASD is the best indicator for predicting the increase in soil permeability by herb roots.There are optimal diameter classes for improving soil permeability in roots of the axial root、the rhizome root and the tiller root herbaceous plants,which are 0.5 mm<D≤1 mm diameter class,0.5 mm<D≤1 mm diameter class,and 1 mm<D≤1.5 mm diameter class,respectively.(3)Taking actual slope protection engineering as the research background,numerical simulation software was used to analyze the impact of three types of root systems on the shallow stability of slopes under different rainfall conditions.The results showed that all three types of root systems can improve the safety factor of the shallow slope,and have a positive effect on the shallow stability of the slope.The stability of the shallow layer of the slope reinforced by the rhizome roots is the best,followed by the axial roots and the tiller-type roots.As the intensity and duration of rainfall increase,the safety factor of the shallow slope gradually decreases.The more effective the reinforcement effect of herbaceous plant roots is under moderate rain intensity,and the rhizome root type’s herbaceous plant is the optimal herbaceous plant for strengthening the slope of the local waste dump.This paper has 43 pictures,13 tables,and 109 references.