| This study took various types of artificial spoilbank as the main object. Firstly, accordingto the generalization of spoilbank by stacking pattern, five types of spoilbank had beenobtained, and these were conical scattered accumulation, dumped along the slope, layeredcompaction, dumped accumulation in strips, top platform. Then the underlying surface modelof the spoilbank and its control parameters were designed. The runoff and sediment yield ofthe former4types of spoilbank were simulated in inner-door rainfall experimental condition,in order to get insight into the soil erosion characteristics of the four types of spoilbank inconstruction project and according to which the standard underlying surface and the value ofmorphological parameters could be achieved. The overall goal of this study is aimed atestablishing the calculation model of the spoilbank’s soil erosion. Three kinds of soil(lightloam, heavy loam, clay), four kinds of soil-stone ratio(pure soil,9:1,8:2,7:3) and four kindsof rainfall intensities(1.0,1.5,2.0,2.5mm·min-1) were included in this experiment, howeveras to this paper, heavy loam was the main object.Main conclusions showed as follow:(1) Four different types of spoilbank in which soil-stone ratio was8:2(mass ratio) weresimulated in inner-door rainfall experimental condition. The results showed that the runoffand sediment yield characteristics had no significant difference among the conical scatteredaccumulation, the layered compaction and scattered accumulation on the top of slope as wellas the dumped accumulation in strips. While the runoff and sediment yield characteristics ofthe top platform type had significant difference from other types. The total runoff and totalsediment yield were higher than other types under2.0,2.5mm·min-1rainfall intensities.According to the analysis and the preliminary research results in this paper, combing the threespoilbanks which had no significant difference on runoff and sediment yield characteristicsinto the conical scattered accumulation type, analyzing it with the top platform type together,then. At last, the conical scattered accumulation type and the top platform type were set as thestandard form of soil loss calculation model.(2) To study the runoff and sediment yield characteristics of these two types, four kindsof soil-stone ratio(pure soil,9:1,8:2,7:3) and four types of rainfall intensities(1.0,1.5,2.0,2.5mm·min-1) were designed. Under different soil-stone ratio, the runoff rate increased in a fluctuating tendency with the rainfalls time, while the law of erosion rate appeared in twotypes with the rainfalls time. That was, when the rainfall intensity was less than2.0mm·min-1,the process line was smooth and the runoff rate changed a little during the whole process. Butwhen the rainfall intensity was higher than2.0mm·min-1, the process line was fluctuating.(3) The total runoff volume and sediment yield increased with the increase of the rainfallintensities no matter how much the soil-stone ratio was. The total runoff volume and sedimentyield decreased with the increase of gravel content under the same rainfall intensity.Compared with the pure soil spoilbank, the total sediment yield of conical scatteredaccumulation type with9:1,8:2,7:3soil-stone ratio decreased by29%，41%，42%under2.5mm·min-1rainfall intensity, and the total runoff volume decreased by6%，15%，-11%.Compared to the same conditions, the total sediment yield of top platform type with9:1,8:2,7:3soil-stone ratio decreased by13%，22%，42%, and the total runoff volume decreased by3%，-2%，23%compared with the pure soil spoilbank.(4) When comparing the total sediment yield under different soil-stone ratio and differentrainfall intensities of the above two spoilbank types, we found that as the soil-stone ratioraised, the total sediment yield of the top platform type increased by6%，29%，40%and5%which compared with conical scattered accumulation type under2.5mm·min-1rainfallintensity. And the total runoff volume increased by28%，0%，44%and0%, respectively. Sothe value of soil and water erosion caused by these two types of spoilbank was apparentlydifferent.Under the condition of individual rainfall, the erosion modulus of conical scatteredaccumulation type was260~1700t·km-2unit projection area, and the erosion modulus of topplatform type was230~1810t·km-2unit projection area. But these values were less than thenormal, so they should be used after the result correction with runoff plot experiment underthe same conditions.(5) Rainfall intensity had a linear function relationship with the average runoff rate aswell as the average erosion rate. What is more, the total sediment yield and runoff volumeaccorded with linear correlation.(6) When the soil-stone ratio of the spoilbank was same, the size of gravel also had aninfluence on the soil erosion characteristics. To be more specific, the total runoff volume of thespoilbank which had larger gravel increased by14%，-3%，13%and11%, and, the totalsediment yield of it increased by25%，22%，14%and25%with the rainfall intensities risingcompared with the spoilbank that had relative small gravel. |
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