交替冻融对土壤临界剪切力和土壤细沟可蚀性的影响

Influence of Freeze-Thaw Effects on Soil Critical Shear Stress and Soil Rill Erodibility

为了揭示冻融作用对土壤临界剪切力和细沟土壤可蚀性的影响,为冻融作用影响下的土壤侵蚀预报提供科学依据,通过室内交替冻融循环试验和变流量微型"V"型水槽人工放水冲刷试验,研究了交替冻融作用影响下土壤临界剪切力和土壤细沟可蚀性的变化特征。试验设计了参照试验(CK),3种交替冻融循环周期处理(1,3,6)和2种土壤质量含水率水平(10%,20%)。结果表明:不同试验处理对土壤临界剪切力和土壤细沟可蚀性的影响程度和趋势不同。当冻融循环周期为1时,土壤的临界剪切力和土壤细沟可蚀性相比参照试验呈现增大的趋势;当冻融循环周期继续增大至3,6时,土壤的临界剪切力和土壤细沟可蚀性相对于参照试验呈减小趋势。当冻融循环周期相同时,10%含水率水平下的土壤临界剪切力和土壤细沟可蚀性均大于20%含水率水平下的土壤临界剪切力和土壤细沟可蚀性。研究为冻融作用影响下土壤侵蚀的预报提供重要参考。

In order to reveal the influence of freeze-thaw effects on soil erosion by water, effects of freeze-thaw on the variation of critical shear stress under the influence of effects of freeze-thaw were studied by alternately freezing-thawing tests and scouring tests. Three kinds of freeze-thaw cycles(1, 3 and 6), two kinds of soil moisture mass fractions(10% and 20%) and control test(CK) were involved. The results show that different experimental treatments have different impact degrees and different impact tendency on soil critical shear stress and soil erodibility;when test soil experiences one freeze-thaw cycle, soil critical shear stress and soil erodibilty show the increasing trend compared to the control experiment;when the freeze-thaw cycle continues to increase to 3 and 6, the soil critical shear stress and soil erodibility show the decreasing trend compared to the control experiment, and when freeze-thaw cycle is equal to 3, soil critical shear stress and soil erodibility were minimum;Soil moisture mass fraction has the significant effect on soil critical shear stress and soil erodibility;when freeze-thaw cycles are same, soil critical shear stress and soil erodibility under 10% soil moisture mass fraction are bigger than the corresponding values under 20% soil moisture mass fraction. These results can provide the support for soil erosion prediction in the context of freeze-thaw cycle.