Analysis Of Mechanical Effects On Ecological Protection Of Slope Shallow In Guanghe Expressway

How to screen the stable slope plant communities compatible with the ecological protection of the slope is among the most urgent problems to be solved in ecological slope protection of expressway slope because of the difference of geological conditions and the variety of plants in the plant slope protection of highway.In this paper,theoretical analysis and laboratory tests are the main research methods.Systematic analysis and evaluation are carried out mainly by theoretical analysis and numerical simulation based on on-site monitoring data.The main research results obtained are as follows:The uni-scholar ecological adaptability test of slope plants was carried out to get the best warm-season herbaceous plants Vetiver,cold-season herbaceous tall fescue,leguminous herbaceous roots for the Lotus,shrub small shoddy beans on the basis of the distribution characteristics of vegetation communities through environmental distribution survey along Guanghe Expressway.Mixed ecological test showed that the main herbaceous plants were bermudagrass and hippophae rhamnoides,and a small amount of tall fescue(or perennial ryegrass)was added as the pioneer plant.The mix use of two or three in pig crotinea beans,pigeon peas,mountain soybeans at the same time contributes to nitrogen fixation and soil improvement.The results of laboratory tests on the highway slope revegetation showed that the initial moisture content of the soil significantly affected the process of rainfall-infiltration-runoff on the slope without vegetation.The change of the initial flow rate of the bare slope reflected the change of the initial soil water content in a most obvious way.The runoff intensity of the slope changed logarithmically with time,and the change of sediment yield was more obvious in the early rainfall and gradually stabilized in the later period.With vegetation slope protection,runoff generation time under different conditions is as follows:bare slope ? white clover>bermudagrass?hippophae;runoff rate of change:bare slope>white clover>bermudagrass>Bare slope>white clover>bermudagrass>Bahia grass;infiltration and vegetation throttling sum:Bahia grass>bermudagrass>white clover>bare slope.Field experiments on the effect of vegetation slope protection on the anti-erosion performance of slope was carried out,the results showed that there was a direct relationship between the slope runoff and the change of rainfall intensity.The runoff of slope increased slowly with the rainfall time,and the initial sediment tended to increase at first and then decrease as time passed by,and then gradually increased to reach the second peak.The total amount of sediment erosion was similar to the s-shaped curve.The better the vegetation coverage was,the smaller the flow velocity of the laminar flow on the slope and less sand produced.A mathmatical model to improve the shear strength of the root-soil complex by plant root was establishe based on the shear strength of soil and the strength of the soil-root complexd.The anchoring mechanical model of plant root and the root of vertical root Body's deep anchoring force equation were propoesed.Meanwhile,a model of soil reinforcement theory based on the equivalent energy consumption theory of shear surface was established and the stability analysis was carried out.The upper bound solution of slope stability safety factor by plastic limit analysis and strength reduction method were discussed.The stability numerical computations of plant slope protection in expressway were carried out.