Study On The Time Effect Of Shrub Roots-Soil Interaction In Bio-Slope

As a new technology of slope protection,the vegetation has been widely applied in the domestic.Long-term stability especially mechanical stability of bio-slope-engineering is worried about because a good answer is failed to give according to existing research.Generally,research for long-term effectiveness of vegetation is far from enough.In view of this,mechanism of shrub roots-soil interaction is researched from the time scale.Theoretical derivation,laboratory test,numerical simulation are applied to analyze the long-term stability of the system,the influence factors of root pull-out resistance,the relationship between root morphology and stability.The main results and conclusions are presented as follows:(1)On the basis of previous research results,the difference between engineering anchor bars and strong roots is pointed out.Roots are living plants,growing in the soil gradually,leading to obvious time effect.The changes of pull-out resistance with time does not take into account if supposing it as Full-length Bonding Rockbolt.(2)Formula of pull-out resistance is deduced from the established model,which considering the change of root radial growth.Results show a power function relationship between pull-out resistance and time,confirming the In-Situ results.(3)The mechanism and applicability of roots-slope model is discussed in detail,and calculation method of safety factor based on longitudinal growth is put forward.The results of an applied example point out that slope stability is in continuous improvement situation.It fits the observation results which confirm the reasonable of model.It provides a theoretical basis for vegetation function in a long term.(4)Results of orthogonal tests show that the main factors affecting vertical pull-out resistance is the quantity of lateral root,length of taproot comes second,density of soil comes next,branching angle has little influence in,namely time effect function highest level in lateral root but lowest in angle.In the mechanical view,the developed root system is more conducive to the stability of the shallow slope.From the time scale,reinforcement effect will be better and better as tillering more lateral root.(5)The fractal dimension varies with the root morphology.Moreover,more complex morphology leading to bigger dimension.Shrub roots play an important role in controlling the slope shallow deformation,make slope from brittle failure to ductile failure.The bigger fractal dimension takes higher safety factor and lower maximum-plastic-strain.A power function relationship between fractal dimension and safety factor increase but a linear function relationship between fractal dimension and maximum-plastic-strain reduction are found in the fitting curve.