Effects Of Soil Structure On Erosion Sediment Yield And Surface Roughness Of Engineering Piles

The soil structure is an irregularly shaped soil mass,which has a certain effect on soil infiltration and runoff and soil sediments on slopes.In this study,the simulated rainfall was applied on the simulated spoil heaps containing the soil structures to study the effect of the soil structure on the erosion and sediment processes of the spoil heaps during continuous rainfall.Besides,the micro-topographic changes and its effects on the slope erosion were also analyzed.At the same time,the field monitoring data was used to preliminarily verify the calculation model of the soil erosion of the spoil heaps in this study.The results are as listed:(1)The flow velocity and runoff rate of spoil heaps showed a trend of "rapid increase-slow increase-stable fluctuation" with time,but the soil structures delayed the runoff initiation and decreased the runoff velocity compared to those of the spoil heaps without soil structures.During rainfall process,the erosion rate of spoil heaps without soil structures increased firstly and then fluctuated relatively stably.For spoil heaps containing soil structures,erosion rate increased initially and then decreased with an obvious peak in the first two rainfall events;in the last rainfall events,the erosion rate increased with fluctuations.The existence of soil structures promotes erosion of spoil heaps slopes.Under the same conditions,slopes containing soil structures are more likely to be eroded by raindrops and runoff.(2)The presence of the soil structure increases the initial surface roughness,surface undulation and surface cutting degree of the slope surface.The first rainfall event had the strongest effect on the micro-topography of the spoil heap surfaces without soil structures,but for spoil heaps with structures,the second rainfall event had the most significant influence.Significant positive correlations exited between the changes in micro-topography factors and sediment production parameters(runoff rate,erosion rate,cumulative sediment yield).(3)Comparing the measured values of the sediment yield in the erosive rainfall of the spoi? heaps on the field with the predicted values of the model,the verification results show that the error value of 87.5% is within the range of-20.0% to 20.0%,and the average error is-2.17%.This can be considered that the prediction accuracy of the model is satisfactory.