不同覆盖条件下坡面流水力学特征试验研究

Experimental study on hydrodynamic characteristics of overland flow under different resistance conditions

【目的】坡面流水力学特性对阐明土壤侵蚀和坡面产沙机理具有重要意义,本试验就不同覆盖条件下坡面的坡面流阻力及相关水力学特征进行了研究,探究不同覆盖条件下坡面流水力学特征,以期为指导水土保持坡面措施合理配置提供理论支持。【方法】试验使用自制定床冲刷水槽,选用不同覆盖度(0%、10%、15%、20%)砾石、草被床面,在不同流量(15~120 L/(min·m))、不同坡度(3°~15°)条件下进行室内定床冲刷试验。【结果】结果表明:(1)不同坡面上流速随着流量、坡度的增大而增大,且相同覆盖度下草被床面流速大于砾石床面流速,最高可达其2.2倍。(2)不同覆盖条件下弗劳德数(Fr)随着坡度的增大而增大,Darcy-weisbach阻力系数(f)随着覆盖度的增加而增加,相同覆盖度下砾石床面f大于草被床面,最高可分别为草被床面的10.9倍。(3)不同覆盖条件下坡面流阻力与流量呈线性正相关关系,相同覆盖度下砾石床面坡面流阻力大于草被床面,最高可达草被床面的2.2倍。(4)坡度与覆盖度对坡面流阻力均有显著影响,坡面流阻力随坡度的增大而增大,随着覆盖度的增大而增大,且呈较好的线性相关关系。【结论】本试验通过对不同覆盖条件下坡面流阻力的研究,可为建立基于径流动力学过程的山坡水文模型和侵蚀物理模型提供一定基础,为指导水土保持坡面措施合理配置提供理论支持。

[Objective]The hydraulic characteristics of overland flow are important for clarifying soil erosion and sediment yield mechanism.In this experiment,the overland flow resistance and related hydrodynamic characteristics of the slope under different resistance conditions were studied.Investigating the hydraulic characteristics of overland flow under different morphological conditions is to provide theoretical support for guiding the rational allocation of soil and water conservation slope measures.[Method]The study used a self-made bed to flush the sink,selecting different coverage(0%,10%,15%,20%)gravel and grass bed surface,and performing indoor fixed bed scouring test under the condition of different flow rate(15–120 L/(min·m))and different slope(3°–15°)[Result]The results showed that:(1)the flow velocity on different slopes increased with the increase of flow rate and slope,and the flow velocity of the grass surface was larger than the flow velocity of the gravel bed under the same coverage,up to 2.2 times.(2)The Froude number(Fr)of different underlying surfaces increased with the increase of slope,and the Darcy-weisbach drag coefficient increased with the increase of coverage.Under the same coverage,the gravel bed surface was larger than the grass bed surface,the highest was 10.9 times of the grass.(3)The flow resistance of different underlying surface slopes was linearly positively correlated with the flow rate.Under the same coverage,the slope flow of the gravel bed surface was larger than that of the grass bed,and the highest was 2.2 times of the grass bed surface.(4)Slope and coverage had significant effects on overland flow resistance.The overland flow resistance increased with the increase of slope,and increased with the increase of coverage,and had a good linear correlation.[Conclusion]Through the study of the slope flow resistance under different conditions,it can provide a basis for the establishment of hillside hydrological models and erosion physical models based on runoff dynamics processes.And it provides theoretical support for guiding the rational allocation of soil and water conservation slope measures.