饱和状态下黄绵土坡面细沟侵蚀可蚀性和临界剪切应力特征  

Characteristics of soil erodibility parameter and critical shear stress on saturated loess soil slope

作　　者：黄钰涵[1,2] 杨梦格 雷廷武 李法虎[1] 王伟[3] Huang Yuhan;Yang Mengge;Lei Tingwu;Li Fahu;Wang Wei(College of Water Resources and Civil Engineering,China Agricultural University,Beijing 100083,China;Guangxi Key Laboratory of Forest Ecology and Conservation,College of Forestry,Guangxi University,Nanning 530004,China;College of Engineering,China Agricultural University,Beijing 100083,China)

机构地区：[1]中国农业大学水利与土木工程学院,北京100083 [2]广西大学林学院,广西森林生态与保育重点实验室,南宁530004 [3]中国农业大学工学院,北京100083

出　　处：《农业工程学报》2022年第17期83-90,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金面上项目(41571257)。

摘　　要：土壤可蚀性参数和临界剪切应力是评价土壤易侵蚀程度和抗水流剪切变形能力的重要指标,目前在黄绵土坡面细沟侵蚀过程中,土壤饱和条件下可蚀性参数和临界剪切应力的变化尚不明确。该研究采用室内土槽模拟冲刷试验确定不同坡度(5°、10°、15°、20°)和流量(2、4、8 L/min)下饱和黄绵土坡面的最大细沟剥蚀率,基于数值法、修正数值法和解析法计算土壤可蚀性参数和临界剪切应力。结果表明,3种方法所得最大细沟剥蚀率均随坡度和流量增加而增大,其中修正数值法和解析法计算的最大细沟剥蚀率更接近。土壤可蚀性参数分别是0.470、0.278和0.256 s/m,土壤临界剪切应力分别为1.502、1.306和1.367N/m~2。修正数值法可提高数值法近似计算的精度,使近似计算结果更接近解析法计算获得的理论值。饱和较未饱和黄绵土的土壤可蚀性参数略有减小(16.83%),而临界剪切应力减小了66.97%,表明土壤饱和对黄绵土土壤可蚀性参数影响很小,但大幅度削弱了土壤临界剪切应力,使得黄绵土坡面饱和后土壤侵蚀更为强烈。此外,饱和黄绵土边坡的临界剪切应力与饱和紫色土坡面相比差异不大,而细沟可蚀性参数大2.26倍,表明土壤饱和对2种土壤临界剪切应力影响程度相似,但黄绵土较紫色土对土壤侵蚀的敏感性更高。研究结果可为饱和状态下不同土壤坡面细沟侵蚀模型参数的优化提供参考。Soil erodibility parameter and critical shear stress are important indicators to evaluate the degree of soil erosion sensitivity and the resistance to the shear deformation of water flow.To date,the change of soil erodibility parameter and critical shear stress is unclear in the rill erosion process of saturated loess soil slope.In this study,the maximum rill detachment rates of saturated loess soil slope were determined by a series of soil scouring experiments in the laboratory under different slopes(5°,10°,15°,and 20°)and flow rates(2,4,and 8 L/min).Then,the numerical,modified numerical,and analytical approaches were utilized to calculate the soil erodibility parameters and critical shear stresses.The results showed that the maximum rill detachment rates calculated by the three methods increased with the increase of slope and flow rate over saturated loess soil slope,and the maximum rill detachment rates calculated by the modified numerical method were similar with those calculated by the analytical method.The soil erodibility parameters were 0.470,0.278,and 0.256 s/m,respectively,and the critical shear stresses were 1.502,1.306,and 1.367 N/m~2,respectively.The modified numerical method improved the calculation accuracy,thus the modified numerical calculation was close to the theoretical value calculated by the analytical method.The soil erodibility parameters of saturated loess soil slope decreased by 16.83%,and the critical shear stresses decreased by 66.97%,compared with those of non-saturated loess soil slope in the same study area.Soil saturation had no significant effect on the soil erodibility parameters,while greatly reducing soil critical shear stress,and then leading to serious soil erosion on loess soil slope.Besides,the critical shear stresses of the saturated loess soil slope were 6.38%larger than those of the saturated purple soil slope,and the soil erodibility parameters of the saturated loess soil slope were 2.26 times those of the saturated purple soil slope.These results indicated that the

关 键 词：土壤 侵蚀 细沟 可蚀性 临界剪切应力 饱和 最大细沟剥蚀率 

分 类 号：S224.2[农业科学—农业机械化工程]