The Research For Limitation & Negative Effect Of Biotechnical Slope Protection

During the interaction with slope soil, vegetation appears to be certain hydro-mechanical effects and provides engineering properties on surface erosion and shallow landslides control and soil shear strength reinforcement. Base on this principle, biotechnical slope protection gets widespread application. However, its effect influenced by many factors, such as vegetation growth environment and slope conditions, particularly, confines of root distribution. The root zones of most plants distribute generally within 1.5 m underground, failure planes of deep seated landslides typically pass well below the rooting zone. Biotechnical slope protection has minimal effect in deep landslide mitigation.There is a mass wasting tendency since slope was formatted. As an important part of exogenic rock action, chemical water-rock interaction (CWRI) promotes slope evolution throughout the whole mass wasting processes. CWRI can give rise to the progressive aggravating of different initial damages in slopes and the structure, mechanical and hydraulic characteristics of mineral, rock and rockmass will all change with CWRI progress. Under many cases, CWRI is the important basis of rainfall triggering landslide events.The circulation rate and chemical components of ground water are two main factors, which can remarkable affect the progress of CWRI. Vegetation is the decisive factor controlling the formation, dimension and lifetime of macropore systems in soils. Root channels, faunal tunnels, shrinkage cracks and interaggregate porosity formatted by vegetation-soil interaction are universal and constitute a relatively stable macropore system in upper slope mass ,which improves markedly the rechange environment of groundwater, make slope to absorb almost all precipitation except interception by vegetation, and promote ground water circulation. The pre-event water giving place to the event water in vegetated slopes make saturation index of water-rock exchange phases to be a low level and chemical water-rock interaction rate be increased. biogeochemical process, such as root breathing and litter degrading, release acidic substances like CO2 and organic acids. Water-soluble organic acids, leachated by the infiltrating rain, transfer into circulation systems of ground water, exchange concentrations of chemical components in it, and make chemical water-rock interaction keep on the proceeding. The contribution of vegetation to CWRI aggravate slope evolution, accelerate slope losing steady and the occurrences of deep seated landslide.Biotechnical slope protection has limited effect in preventing deep landslide mitigation. On the contrary, the contribution of vegetation to deep landslide preparation is notable. To sum up, vegetation has negative effect in the slope stability.