人工降雨和放水冲刷条件下紫色土坡面产流产沙特征分析

采用可变坡的3 m×1 m土槽进行人工降雨和放水冲刷试验,在不同坡度(5°~20°)、不同雨强(0.6~2.5mm/min)和放水流量(1.6~7 m3/s)情况下,对紫色土坡面的产流产沙特征进行了研究。结果表明:放水冲刷试验中径流流速从坡上到坡脚表现出先增加后减小、逐渐增大和逐渐减小3种趋势,而人工降雨试验则恰恰相反,径流流速从坡上到坡脚表现出逐渐增大的趋势;15 min是2种试验方法产流过程稳定的临界时间;人工降雨试验径流含沙量稳定的时间介于5~50 min之间,放水冲刷试验含沙量稳定的临界时间为20 min。试验成果可为后续紫色土侵蚀相关研究提供数据支持。

Characteristics of Runoff and Sediment Yield of Purple Soil Slope Surface in the Presence of Artificial Rainfall and Scouring

Soil tank (3 m ×1 m)of variable slope was taken for artificial rainfall and runoff scouring test.The fea-tures of runoff and sediment yield on purple soil slope in the presence of different slope gradients (5°~20°),rain-fall intensities(0.6~2.5 mm/min),and scouring flow rates(1.6 ~7 m3/s)were researched.Results indicate that in scouring test,the runoff flow velocity from slope top to slope toe changes in three tendencies:first increases and then reduces,progressively increases,and progressively reduces;whereas for artificial rainfall test,the runoff flow velocity gradually increases from slope top to slope toe.The critical time of runoff getting stable in both tests is 15min;whereas for sediment concentration,the time of getting stable is between 5 ~50min in artificial rainfall test and 20min in scouring test.