Kinetic Experimental Study On The Separation Process Of Soil In The Rills Of Loess Slopes

The severe soil erosion on the Loess Plateau has degrawn soil quality and the sharp decline of land productivity has become one of the primary environmental problems in China.Rill plays an important role in soil erosion and sediment yield on the Loess plateau.Rill flow separation is the premise of rill erosion,controlling the strength of rill erosion.The separation ability and the separation rate of the rill were affected by slope,flow and hydrodynamic parameters,Study on the coupling relationship between rill separation ability and separation rate and hydrodynamics,Which can further reveal the process of rill erosion on the slope,clarify the mechanism of rill erosion,lay the foundation for the establishment of slope rill erosion model,promote the development of slope ridge erosion research,And to provide a scientific basis for controlling the rill erosion on the loess slope and controlling the soil erosion on the slope.Based on the analysis of previous research and field observation data,this paper makes a simulation experiment on the flow rate of rill sediment flow in Loess slope,Study on the mechanical properties of slope water rill sediment,coupling relationship between rill sediment separation rate variation and sediment separation rate and hydrodynamic parameters,and the establishment of rill sediment flow separation factor model and dynamic model of rill erosion process model is established to provide scientific support,the conclusions are as follows:1.In the condition of all sediment concentration,flow velocity,water depth,resistance,Reynolds number,shear stress and section unit energy increases with increasing flow rate,the Froude number in the small flow rate stage increased rapidly,the fluctuation trend in large flow stages;in all flow conditions,flow velocity,Reynolds number,Froude number and section unit energy with sediment concentration increases,water depth,resistance coefficient and shear stress increases with the increase of sediment concentration;the effect of flow rate on hydrodynamic parameters than large sediment;and rill sediment flow are jet,flow transition flow.2.1n terms of different grain size and sediment concentration,rill sediment flow separation with flow rate increasing;in different flow rate and particle size under the condition of rill sediment separation rate with sediment concentration decreases;in the condition of different flow and sediment concentration,rill sediment flow changes with the size of the separation rate is not obvious;rill sediment separation rate and sediment concentration,a three Yuan linear relationship between flow rate and particle size,the correlation formula is:Dc=0.1327-0.00088s+ 3517.682q-2.02009p(R2=0.673 676,P=0.05,NE= 0.6737),the flow rate has the greatest influence on the flow rate of the rill sediment flow,followed by the sediment concentration,the smallest impact on the particle size.3.The separation rate of the water in the gully contains an increase with the flow rate,the unit water power and the unit energy of the section.With the shear stress,the flow power increases first and then decreases.through further analysis,section unit energy is selected in one of the best indicators,select section unit energy to explain the rill sediment sediment separation rate,followed by the unit stream power,rill sediment flow rate and separation section unit energy relationship between available cubic function relation fitting,the fitting relationship is:Dc=0.0612+ 0.5085E-0.7951E2 + 0.6625E3(R2=0.584,P=0.01,NE=0.5843)。...