辽西春季解冻期褐土工程堆积体坡面侵蚀特征

Slope erosion characteristics of brown soil engineering accumulation in spring thawing period in western Liaoning

为揭示辽西春季解冻期工程堆积体土壤侵蚀特征,以褐土工程堆积体为研究对象,采用室内模拟放水冲刷试验对春季解冻期褐土工程堆积体坡面侵蚀过程进行研究。结果表明:在冻融作用影响下坡面产沙量平均增长22.5%,加剧工程堆积体坡面的侵蚀,解冻时间越长,坡面侵蚀越严重。与未经冻融处理的对照坡面对比,受冻融作用影响的坡面在20°和25°坡度下,Darcy-Weisbach阻力系数f分别平均下降75.40%和71.33%,弗劳德数Fr平均增加44.4%和32.0%。侵蚀量、平均横断面积与放水冲刷量之间呈现极显著正相关,f与放水冲刷量之间呈现极显著负相关,Fr与放水冲刷量之间呈现显著正相关。受冻融影响的堆积体坡面侵蚀沟沿坡下至坡上呈“宽深-窄深-宽浅”式发展。在冻融作用的影响下,工程堆积体坡面在侵蚀过程中,相较于未经冻融影响的坡面,其坡面径流流速更快,并且径流阻力更小,侵蚀更为剧烈。

[Background]Soil erosion in production construction projects is a typical man-made accelerated erosion.Fuxin city is located in the semi-arid region of western Liaoning,with brown soil and sandy soil as the main soil types,and is the most fragile ecological environment with serious soil erosion.Therefore,this paper selected the accumulation body of the Xihe River regulation project in Fuxin city as the research object,and studied the slope sediment characteristics,hydrodynamic parameters and erosion ditch morphology of the accumulation body under the influence of freeze-thaw,aiming to provide basic parameters and technical basis for the layout of soil and water conservation measures in production and construction projects.[Methods]The soil used in this experiment was obtained from the river soil of the river regulation project in Fuxin city,Haizhou district,and after sieving and preparation,it was filled into the soil tank in layers of 5 cm.The erosion process of slope of cinnamon soil engineering in spring thawing period was studied by simulating water flushing test in laboratory.Measurement of flow rate by dyeing method(KMnO_(4))and erosion gully morphology by straight edge.SPSS 20 was used for data processing,and Autocad2012 and Excel were used for drawing.[Results]Under different thawing times,the sand production process on the slope of the mound all showed a trend of first increasing and then stabilizing.The average increase in sand production on slopes under the influence of freezing and thawing was 22.5%,which increased the erosion of the slopes of the engineered accumulation.The longer the thaw was,the more severe the slope erosion was.The different slopes affected by freezing and thawing showed a decrease in the Daicy-Weisbach coefficient of resistance f by 75.40%and 71.33%and an increase in the Froude number Fr by 44.4%and 32%,compared to the control slope.There was a very significanty positive correlation between the amount of erosion and the average cross-sectional area and the water scouring amount,a very significanty negative correlation between f and the water scouring amount,and a significanty positive correlation between Fr and water scouring amount.Erosion gullies on the slopes of freeze-thaw affected mounds developed in a“wide deep-narrow deep-wide shallow”pattern down to the top of the slope.[Conclusions]In the northern areas of China affected by freezing and thawing,the freezing and thawing effect will accelerate the flow rate of slope runoff and reduce the slope resistance parameter.During erosion,the slope of an engineered stockpile presents a faster runoff rate and less resistance to runoff than a slope not affected by freezing and thawing,resulting in more intense erosion.