Study On The Mechanism Of Soil Aggregate Fragmentation And Cementation Under Rainfall Erosion

The formation and stability of soil aggregates are affected by soil cementing substances.Understanding the composition,distribution,content and interaction of soil cementing substances and soil particles under raindrop splashing thin-layer runoff is crucial to improving the formation and stability of soil aggregates.Sex matters.This study takes the loess soil and loess cotton soil in the Loess Plateau as the research objects.By setting raindrops with different diameters to hit the thin-layer runoff,the effects of the fragmentation and migration of soil aggregates and the change of soil aggregate cementing agent content under the impact of raindrops on the thin-layer runoff are explored.To clarify the relationship between the stability of aggregates and the content of cement,and the degree and possible mechanism of the influence of cement on aggregate breakage.The main conclusions are as follows:(1)The diameter of raindrops has a significant impact on the amount of soil aggregate erosion,which shows that the amount of aggregate erosion increases with the increase of raindrop diameter under the same thin-layer runoff,while under the same raindrop diameter,different thin-layer runoff affects the erosion of aggregates.amount had no significant effect.The particle size of 0.053-0.25 mm has the least amount of aggregate loss of loess soil,and the erosion amount of loess soil is mainly <0.053 mm particle size.Under the same hydraulic erosion,the erosion amount of the loess soil is greater than that of the loess soil,and the stability of the loess soil is higher than that of the loess soil.(2)After hydraulic erosion,the contents of organic carbon,six-carbon sugar,free iron oxide,and free alumina in the aggregates of the loess were higher than those of the loess,and the content of calcium carbonate was lower than that of the loess.Rainfall erosion can significantly reduce aggregate hexa-carbon sugars.Loess soil is more likely to lose hexacarbon sugars and free iron oxide than sloppy soil.The loss of calcium carbonate in sloppy soil is higher than that of loess soil under water erosion.Under the rainfall erosion,the free alumina in the sloppy soil showed a decreasing trend,while that in the loess soil showed an increasing trend.The five cementing agents have a significant effect on the erosion amount of the soil aggregates under different particle sizes.Except for the six-carbon sugar,the other four cementing agents have a significant effect on the loss of loess soil under different particle sizes.Regression analysis found that hexacarbon sugar and free iron oxide are the most important cementing agents affecting the erosion of loess soil aggregates at a particle size of0.053-0.25 mm,and calcium carbonate is the most important cementing agent affecting the erosion of loess soil aggregates at a particle size of 0.053-0.25 mm The most important binder.(3)The MWD and GMD values of the soil decreased with the increase of the raindrop diameter,while the PAD and D values increased with the increase of the raindrop diameter.The MWD value of loess soil fluctuates with the increase of raindrop diameter,the GMD value increases with the increase of raindrop diameter,the PAD value decreases with the increase of raindrop diameter,and the D value increases with the increase of raindrop diameter.And reduce.(4)There is a significant relationship between the soil aggregate stability index MWD,GMD,PAD,and D and organic carbon,six-carbon sugar,and calcium carbonate,but there is no significant relationship with free iron oxide and aluminum.relation.There is no significant correlation between the stability index of loess soil aggregates and the five cementing substances.Organic carbon,six-carbon sugar,and calcium carbonate are the cementing agents that significantly affect the stability of loess aggregates,and none of the five substances studied significantly affect the stability of loess soil.