工程堆积体坡面细沟侵蚀形态空间变化

Spatial Variation of Rill Erosion Morphology on the Slope of Engineering Accumulation

为揭示工程堆积体坡面细沟形态空间变化规律以及细沟形态参数与坡度和流量之间的关系,选取5,9,13,17 L/min放水流量,对24°,28°和32°堆积体进行放水冲刷试验,运用沟长、沟宽、沟深等指标描述细沟发育过程。结果表明:在24°和32°堆积体坡面,放水流量最大时,沟长发育最快;在相同放水流量条件下,随着坡度增大沟长发育越变缓。在24°堆积体坡面,沟宽在所有放水流量条件下呈现差异化发育,剧烈发育集中在1~6 m,相对平稳发育在6~9 m;在28°和32°堆积体坡面,放水流量为5,9,13 L/min时,沟宽在3~9 m发育相对平稳。在试验条件下,坡面沟深发育整体呈现减小趋势,波动变化集中在1~5 m;在同一坡度条件下,平均沟宽和沟深均随放水流量增大而增大,而在同一流量条件下,除放水流量为5 L/min时,平均沟宽和沟深随坡度无显著差异,表明流量对细沟形态指标影响大于坡度。沟宽在坡面不同位置发育基本一致,沟深由坡上到坡下却逐渐变小,坡面细沟侵蚀形态可概化为“楔形”。研究结果对于生产建设项目工程堆积体坡面防护措施的合理配置具有重要意义。

In order to explore the spatial variation of rill morphology on slope of engineering accumulation,the relationships between rill morphology parameters and slope gradients and flow discharge were analyzed.In this study,scouring-erosion experiments were conducted on steep slopes of engineering accumulation under different slope gradients(24°,28°and 32°)with different flow discharges(5,9,13 and 17 L/min).The indicators such as rill length,rill wide and rill depth were used to describe the rill development process.The results indicate that the rill length develops fastest when flow discharge is 17 L/min under the slope gradients of 24°and 28°,while the development of rill length becomes slower with the increase of slope gradients under the same flow discharge;the rill width presents a differentiated development on the slope of 24°under all flow discharges,which can be divided into two stages:a rapid development stage in 1~6 m and a subsequent slow development stage in 6~9 m,while the slow development in 3~9 m of rill width on the slope gradients of 24°and 28°is observed under discharges of 5,9 and 13 L/min;under the experiment conditions,the development of rill depth on the slope shows a decreasing trend,and the fluctuation is concentrated in 1~5 m;the averages of rill width and depth both increase with increase of flow discharge under the same slope condition;in contrast,except for 5 L/min,there are no significant differences in average of rill width and depth between slope gradients under the same flow condition,indicating that the effect of flow discharge on rill morphology parameters is greater than that of slope gradient;the rill width develops basically consistent in different positions of the slope,while the rill depth presents a decreasing trend from the upslope to downslope;the rill erosion morphology on the slope of engineering accumulation can be classified as‘wedge-shape’.These results have important implication for the reasonable allocation of protective measures on slope of engineering accumulation in production and construction projects.