摘要
采用室内试验,用平均粒径约2cm的砾石,在长4m、宽15cm、高50cm的水槽内堆积厚为5cm的砾石层,在坡度为4°、8°、12°和流量为3、6、12L/min条件下,距离电解质脉冲发生器0.3、0.6、0.9、1.2、1.5m处放置探针,测量电导率变化过程,计算水流的最大流速、优势流速和平均流速,并用染色剂示踪法对比砾石层中水流的最大测量流速。结果表明,试验所用各工况,流量对流速的影响不显著,坡度增大,流速明显增大。试验条件下,水流的优势流速变化范围为0.031～0.070m/s,优势流速与最大流速的比值稳定,在0.81～0.83之间。平均流速与优势流速的比值随坡长的增加逐渐增大,增长的速率逐渐减小并趋于稳定。平均流速与最大流速的比值在0.68～0.78之间,并随距离的增加稍有增大。
Mountainous soils often contain large amounts of gravels which impact rainfall infiltration, runoff and soil erosion. The flow velocity within gravels is of great importance for research of soil erosion process in rocky mountainous areas. Dye tracer method was commonly used to measure the leading edge velocity. The gravels of about 2 cm in diameter were used to fill to a thickness of about 5 cm in a flume of 4 m long, 15 cm wide and 50 cm high. Five sensors were used to measure the electrolyte conductivity change process at 0.3, 0.6, 0.9, 1.2 and 1.5 m from the solute injector under three flow rates of 3, 6 and 12 L/min and three slope gradients of 4~, 8~ and 12~. The peak, mean and leading edge velocities were computed before comparisons were made with those measured by using dye tracer method. The results showed that under different conditions, flow velocity was not significantly affected by discharge rate, but notably affected by slope~ With the increase in slope, flow velocity increased from 0. 031 m/s to 0. 070 m/s. The peak velocities were 0.81 -0. 83 times of the leading edge velocity, regardless of the effect of slope and flow rate. Mean velocities were about the same as the peak velocities, which were 0.68 -0.78 times of the leading edge velocities and increased with distance increasing. The ratio of mean velocity and leading edge velocity can be also used to calculate the flow velocity within gravels measured by dye tracer method. The method should be useful to understand the hydrodynamics of water flow within gravel layers.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2015年第4期141-146,共6页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金资助项目(41230746)
关键词
砾石层
平均流速
优势流速
最大流速
电解质示踪法
Gravel layer Mean velocity Peak velocity Leading edge velocity Electrolyte tracermethod
