Study On Reinforcement Effect Of Plant Roots On Red Clay Slope

There are many problems on adopting traditional rigid protective measures to reinforce red clay slope,such as easily damaged structure,surrounding ecological environment destruction,glare from sunniness,while the problems can be effectively avoided by taking the new ecological slope protection.The new protection can enhance the stability of slope,through which disasters such as landslides and mudslides could be prevented,reducing water and soil loss;or protect and cure the surrounding environment,improving microclimate locally.The paper,based on theories of plant root reinforcement and anchoring,as well as the combination of plant roots morphology and its distribution,conducts analysis on reinforcement effect and anchoring effect of plant root strengthening red clay slope through indoor direct shear test and finite-element numerical simulation,which discusses rules for how shear strength of red clay changes with root contents in different moisture contents.Based on the finite element analysis on factors influencing anchoring effect of woody plant roots the paper discusses some key elements influencing the slope stability,such as length of single root,horizontal distance between single root and the bottom of slope and angle between single root and horizontal direction by means of orthogonal test and then draws some main conclusions as following:(1)The paper,based on basic physical properties of red clay by a series of soil mechanics test,studies shear strength of red clay in southern Anhui under different water contents by means of fast shear test.It analyzes rules for how water contents and root contents influences shear strength of root-soil composite by indoor direct shear test in accordance with prepared root-soil composite shear specimens.(2)With the assistance of MATLAB software,surface fitting is conducted to shear experimental data for root-soil composite,obtaining dyadic and square fitted equation of added value of cohesive force changing with water content and root content.(3)According to the results of finite element analysis,the order of slope stability is as following:slope reinforced by woody plant roots?slope reinforced by herbaceous plant roots?Original slope.In accordance with slope stability factors,woody plant is better than herbaceous plant in terms of reinforcement,and in terms of limiting horizontal displacement of slope,herbaceous plant is worse.(4)Through the analysis of finite element model under different working conditions,it finds that tap root is as main position while lateral root as assistance in anchoring of main taproot-type woody plant.And reinforcement effect would be in the best conditionto allocate roots at the bottom of slope,while the worst condition as roots being allocated at the top of slope;moreover horizontal spacing of roots should not be less than 2.5 m.The reinforcement effect is better to adopt main taproot-type woody plant at slope with its height less than or equal to 15 m and its gradient less than 1:0.75.(5)Based on finite element analysis results,the order of factors influencing slope stability is as following: horizontal distance from single root to the slope bottom ?length of single root?angle between single root and horizontal direction.From the test,value of single root anchoring is at its optimum as single root being 4m,horizontal distance from single root to the slope bottom being 0m,and angle between single root and horizontal direction being 45°.