工程堆积体坡面工程措施减流减沙效应的试验研究

摘要

In order to investigate the effects of engineering measures fish-scale pit and level terrace on the reduction of overland flow and sediment by the steep slope of engineering accumulation,in this paper,the runoff scouring experiments were used to simulate the runoff and sediment process in the steep slope of engineering accumulation with the flow of 40 L/min and slope of 24°,28°,and 32°.The results showed that (1)fish-scale pit and level terrace can reduce slope runoff and increase soil water in-filtration at the early stage of the production flow;(2)the interception ability of two measures decreases after the production flow and the two measures even have adverse effects;(3)fish-scale pit can result in two peaks in runoff intensity with the con-tinuation of discharge time,and soil erosion rate has two peaks as well,which occur after 6 and 24 minutes of production flow;(4)level terrace can lead to the staged variation of runoff intensity with discharge time;(5)the water logging phenomenon ap-pears in the level terrace and fish-scale pit in the later period of production flow,soil infiltration rate is negative,which indicates that soil water recharges to runoff in the early stage of production flow and leads to the increasing of slope erosion;and (6)fish-scale pit and level terrace have lowered the correlation of power function of cumulative sediment yield and runoff.For the drain-age design of steep slope,the maximum runoff and amplification effect of slope measures are needed to be considered.For the runoff regulation system of steep slope,the timeliness of the protective benefit of engineering measures is needed to be considered.%为了探究工程措施水平阶和鱼鳞坑对工程堆积体陡坡坡面减流减沙和产沙过程的影响,采用径流冲刷试验,在流量为40 L/min,坡度24°、28°、32°范围内对工程堆积体陡坡坡面产流产沙过程进行模拟研究,结果表明：水平阶和鱼鳞坑在产流前期具有滞缓坡面径流、增加土壤水分入渗的作用；在产流之后两种措施对坡面径流的拦蓄能力微弱,甚至起到放大的作用；其中鱼鳞坑使坡面径流强度随放水时间的延续出现两次峰值,其坡面土壤剥蚀率变化过程也出现两次峰值,即产流后第6 min 和24 min；水平阶使径流强度随放水时间的变化呈现阶梯式变化,变化的时间点不同坡度不尽相同；产流后期,水平阶和鱼鳞坑出现水毁现象,土壤入渗率出现负值,表明产流前期的土壤水补给径流,导致坡面侵蚀加剧；鱼鳞坑和水平阶使累积产沙量和累积径流量的幂函数相关性降低。对于陡坡坡面排水渠的设计不仅要考虑最大径流量还要考虑坡面措施的放大作用,对于陡坡坡面径流调控体系而言,工程措施防护效益的时效性值得考虑。