冻融循环对风沙土物理性质及抗冲性的影响试验

为揭示冻融循环对土壤物理性质及抗冲性的影响,以内蒙古坡耕地风沙土为研究对象,控制冻融循环次数(0~10次)和土壤质量含水量(6%,9%,12%)2个因素,在室内模拟野外冻融循环和径流冲刷过程,定量分析冻融循环对土壤含水量、容重、孔隙度及土壤抗冲性的影响规律。结果表明:(1)土壤含水量随冻融循环次数增加呈缓慢增加的趋势,增加幅度为0.51%~0.87%,且高含水量土壤增幅比低含水量土壤大;(2)随冻融循环次数的增加,土壤容重和孔隙度分别呈缓慢减小和增大趋势,且变化幅度逐渐降低,最后达到基本稳定的状态,达稳定状态后的土壤容重比未冻融土壤小(0.05±0.01)g/cm~3;(3)当冻融循环次数相同时,高含水量(12%)的土壤容重比低含水量(6%)小,而孔隙度和土壤抗冲性的降低幅度与之相反;(4)冻融循环次数对风沙土抗冲系数具有显著影响,试验土样抗冲性随冻融循环次数的增加呈显著降低趋势,但是第6次冻融循环后,试验土样的含水量、容重、孔隙度及抗冲性的变化均逐渐趋于稳定。研究结果可为季节性冻融区土壤侵蚀机理研究提供参考。

Effects of Freeze-thaw Cycles on Aeolian Sand Soil Physical Properties and Soil Anti-scouribility

Freeze-thaw cycle is one of the significant characteristics of soil thawing process in the area of seasonal freeze-thaw.In order to reveal the influence of freeze-thaw cycles on soil physical properties and soil anti-scouribility,aeolian sandy soil collected in a sloping farmland in Inner Mongolia was taken as the research object.Two factors of freeze-thaw cycles (0 to 10) and soil water content (6％,9％ and 12％) were controlled to simulate field freeze-thaw cycles and the runoff scouring process.The influence of freeze-thaw cycle on soil water content,bulk density,porosity,and soil anti-scouribility was analyzed quantitatively.The results showed that:(1) Soil water content increased with the increasing number of freeze-thaw cycles,and was increased by 0.51％ to 0.87％.The increasing extent for the soil with high water content was greater than for the soil with lower water content.(2) With the increasing number of freeze-thaw cycles,soil bulk density and porosity were decreased and increased slowly,respectively,with the extent of change decreasing gradually,and finally reached a basically stable state,under which soil bulk density was 0.05-±0.01 g/cm3 lower than the soil not subjected to freeze-thaw;(3) When the soil had the same numbers of freeze-thaw cycles,soil bulk density of the soil with high water content (12％) was greater than that of the soil with low water content (6％),but the porosity and soil anti-scouribility showed the opposite trend;(4) The number of freeze-thaw cycle had a significant effect on soil anti-scouribility.Soil anti-scouribility significantly decreased with the increasing number of freeze-thaw cycles.However,after sixth freeze-thaw cycle,the change of water content,bulk density,porosity,and soil anti-scouribility gradually decreased.The results can provide a reference for studying the mechanism of soil erosion in the seasonal freez-thaw area.