The Analysis Of Development Of Rill Cross Section Morphology And Mechanism On Slope

Slope erosion is serious on the Loess Plateau Area of China.Rill erosion is an important stage in the turning point occurred on the amount of soil erosion.Rill cross section morphology is formed by the erosion of rill flow to underline surface and the collapse of rill wall,it's directly affected by the flow energy,sediment concentration,soil texture and other factors,at the same time soil texture,sediment-laden flow affects flow erosion,thereby restricting the cut intensity of rill erosion.Firstly,The flume scouring experiment indoors was conducted to simulates the change of rill cross section morphology and rill flow sediment concentration varies with slope,slope length and the development process in the development process of rill test to reveal the relations between rill cross section morphology and rill flow sediment concentration.Then to simulate the incision of rill flow by adjusting the slope to get a different scouring ability in scouring soil box.,at the same time,to simulate residual scouring ability of rill.The main results are the following:1.Rill cross section continues to darken with the development process of rill;With the slope increase,rill cross section morphology developed from wide-shallow to narrow-deep and then to deep U-shaped;With slope length increases,rill cross-sectional area and depth were both reduced.Each rill cross section morphology index ? basically tend to increase with the development of rill under the five slope.The rill cross-section morphology coefficient distribution is normal,the factor value is mainly between0.45 to 0.92.Rill cross section appears most times when the rill cross section morphology index ? was in 0.6~0.8.2.With slope increasing,the scouring velocity of five kinds of soil increased,showing an exponential function;The scouring velocity of five kinds of soil also increased with the increase of flow velocity,showing an exponential regression;The erosion-resisting coefficient of five kinds of soil decreased with increasing slope which was shown an exponential regression relationship.The erosion-resisting coefficient and the flow velocity were shown inverse correlation variation.The erosion amount per minute of five kinds of soil basically increases with increasing slope.With the passage of time,the erosion amount per minute substantially decreased and the larger the slope was,the greater the amount of pre-washed.With the increase of sediment concentration of flow,the erosion-resisting coefficient of five kinds of soil are gradually reduced and showed a good linear fitting relationship.The erosion-resisting coefficient of Yang ling soil decreased most with the increasing sediment concentration of flow.The decrease amplitude was Yangling soil> Zhouzhi soil> Yan'an soil> Zhidan soil> Jingbian soil.That is,the better soil antiscourability the more significant change of the erosion-resisting coefficient with the flow of sediment concentration change.3.Under the conditions of 700 L / h,the sediment concentration of each section of rill flow increases with increasing slope and can be described by the power function;The sediment concentration of rill flow increases with increasing slope length and can be described by the power function;Under different slope conditions,the sediment concentration of each section of rill flow increase with the increase of flow velocity and can be used to fit linear equation relationship.The greater the sediment concentration of rill flow was,the greater rill cross section morphology index ? was.The larger the slope was,the greater growth rate of rill flow sediment concentration increased with increasing cross section morphology index ?.