砾石含量对崩积体坡面细沟横断面形态影响

Effects of Gravel Content on Rill Cross Section Morphological in Colluvial Deposit Slope

为研究砾石含量对崩积体坡面细沟侵蚀的影响,采用室内放水冲刷试验,研究了30°坡面下不同冲刷流量(2,4,8,12L/min)对4种土石混合崩积物(0,10%,30%,50%砾石质量比例)冲刷过程中细沟横断面形态特征。结果表明:(1)随冲刷时间的增加,深度增加速度大于宽度增加速度,横断面向窄而深发展。(2)坡顶细沟横断面深度较大,接近“V”形,侵蚀严重;坡底细沟横断面深度较小,侵蚀较弱;细沟横断面形态指标η随坡长增加出现波动变化。(3)横断面深度随砾石含量增加总体呈先减小后增大趋势,10%砾石含量坡面细沟深度最小;10%砾石含量坡面细沟横断面形态指标η变化范围最大;临空面在10~15cm深度开始发育,低砾石含量土壤更有利于临空面发育。

In order to explore the influence of gravel content on rill erosion of colluvial deposit slope,the combination souring tests were conducted.This paper studied the morphological characteristics of rill cross section during scouring of four kinds of soil-rock mixed colluvial(gravel mass ratios of 0,10%,30%and 50%,respectively)with different scouring flow rates(2,4,8 and 12 L/min,respectively)under slope gradient of 30°.The results showed that:(1)With the increase of scouring time,the increasing speed of depth was greater than that of width,which made the shape of rill cross section develop toward narrow and deep.(2)The depth of rill cross section was large on the top of slope,which was similar to the“V”shape,and the erosion was severe.The depth of rill cross section was small on the bottom of slope and the erosion was relatively mild.The morphological indexηof rill cross section fluctuated as the increase of slope length.(3)With the increase of gravel contents,the depth of cross section decreased first and then increased.The depth of rill was shallowest on the slope with 10%gravel content.The morphological variability of cross section was maximum on the slope with 10%gravel content.The free surface began to develop at the depth of 10~15 cm,and the soil with low gravel content was more conducive to the development of the free surface.