Analysis Of Soil Reinforcement By Root Based On Representative Volume Element Homogenization Method

Plant roots can reinforce surface soils and mitigate shallow landslides.In order to evaluate the effectiveness of root reinforcement and slope stability,the root-soil composite was regarded as a natural fiber-reinforced composite material,and the representative volume element(RVE)method was introduced to directly construct the three-dimensional constitutive relation of root-soil composites via a RVE.The RVE method quantifies the enhancement effect of the root system on the soil and explores the feasibility of its extension to study root morphology.The theoretical results obtained by the RVE method were verified by direct shear tests and repeated shear tests with different embedded roots.Based on the RVE three-dimensional theoretical model,the influences of soil elastic modulus,soil moisture content,root elastic modulus,root filling fraction,and root morphology on the root-soil composite equivalent properties and slope displacement were investigated.Finally,in order to verify the accuracy and efficiency of the equivalent mechanical parameters of the root-soil composite obtained by the RVE method for evaluating the slope stability,a three-dimensional simulation slope model was established to simulate the mechanical deformation of the root slope and no-root slope response,the influence of the parameters of the root and soil on the slope displacement was further explored.The results showed that:(1)The RVE method can be used to accurately evaluate the equivalent elastic properties of root-soil composites and the alterations of the strength parameters c and φ.The strengthening effect of the roots on the soil not only improves the cohesion c,but also changes the internal friction angle φand elastic parameters.However,the Wu model cannot evaluate the equivalent elastic parameters of the root-soil composite.The difference for the increase ratio of the shear elastic modulus of the root-soil composite predicted by the RVE method and the repeated shear tests is only 0.24%.The difference for c and φ is only 2.45 k Pa and 3°,respectively.The c calculated by the Wu model is overestimated about 5 times compared to the test results(2)At the slope scale,combining the RVE homogenization theory with numerical simulations is more efficient(the element number decreased by 96.24–96.67%).(3)The physical parameters of roots and soils,root filling fraction,root morphology,and other factors affect the mechanical parameters of the composite,which,in turn,affect the slope’s displacement and stability.(4)The plant root system can modify the stress field of the shallow slope,reinforce the root-soil composite area,reduce the vertical displacement of the slope obviously,and improve the safety factor of the slope.The Wu model runs the risk of overestimating slope stability.This investigation provides a new way to consider root-soil composites for root-reinforced slopes from the perspective of periodic composite materials.And it has certain guiding significance for the reasonable planting of trees.