Study On Splash Erosion Characteristics In Collapsing Hill Of Different Levels

Collapsing wall is an important part of the Collapsing hill erosion, in order to study splash erosion characteristics in different soil layers of collapsing wall, a raindrops generator was made to simulate different diameter raindrops, and this paper studied the splash amount, different characteristics of the soil particles and separation characteristics of aggregate water stability in different soil layers of collapsing wall, which under different raindrop size and raindrop intensity. And this study, based on 3 D scanning technology,analyzed the characteristics of collapsing wall’s three soil layers. The results showed that:(1) Relative to the other two layers, along with the rising of the rainfall intensity, the splash amount in different soil layers of collapsing wall was gradually increasing, the increased rate of red soil splash amount gradually increasing with the raindrop kinetic energy increases, the increased rate of splash amount in sandy soil layer was gradually decreasing, the increased rate of clastic soil splash amount has been increased after decreased trend. As the rain continues, the splash amount of the three layers was increasing, however, the splash erosion rate generally presented the tendency of decrease. Rainfall duration has a biggest influence on red soil splash erosion, soil layer the second, clastic was the smallest. Splash amount in different soil layers of collapsing wall was a positively logarithmic function relation with the raindrop kinetic energy.(2) The soil particles of splash erosion were concentrated distribution in the splash erosion range of 0 to 5 cm, Among them, the red soil splash erosion with the rate change of rain intensity was the maximum, the second was the clastic, and the minimum was the sand layer. Analyzed by two-factor variance, the soil characteristics of splash erosion amount was greater than the influence of rain intensity. The mass percentage of particles with size of 0.05-2mm was the most, while the mass percentage of particles with size less than 0.002mm was the least, which can speculate the size range that makes splash amount reaches the maximum. With the increase of splash erosion distance, soil particles with size more than 2mm were the most difficult to be spattered move, while soil particles with size of 0.002-0.05mm and with size less than 0.002mm were the most vulnerable to be spattered move. Enrichment of aggregate rate in different soil layers of collapsing wall showed a trend of decrease after the first increase with the decrease of the Splash erosion particle fraction.(3) The value of the splash erosion amount, which in different soil layers of collapsing wall, calculated by 3 D laser scanner was larger than the dry method, while the results of independent sample t-test showed that the three layers’ splash erosion amount that using the two methods calculated did not differ significantly. Under the condition of small rain intensity test, splash erosion depth of sand layer, which among three layers of collapsing wall, was 1.5 cm, and sand was the most vulnerable to be splashed layer. The splash erosion depth of red soil layer was minimum, only 0.5 cm, this layer had a stronger ability to resist erosion, it suggested that a specific soil types in a certain scope of raindrop diameter, small rain prone to splash erosion. Under the big rain intensity test conditions, Large Numbers of aggregate structure in red soil was destroyed, the splash erosion depth was the biggest in this stage, which was 2.5 cm, while the sandy soil layer and elastic layer were relatively small, only 1.5～2 cm. Three soil surface roughness value changes before and after the rain splash erosion, are increased with the increase of rain intensity showed a trend of decrease after the first increase. Overall, the change of the surface roughness value of the minimum red soil, sandy soil layers, the change of the clastic value maximum.