明渠底槽栽植高羊茅对槽底土体抗冲刷的影响

Anti-scouring Effect of Tank Plant Tall Fescue on Open Channel Bottom

为研究明渠底槽在栽植高羊茅的情况下,高羊茅对底槽的土体抵抗水流冲刷能力的影响作用,为实际工程中的植草防护提供理论的数据。以辽宁省常用的护坡植物高羊茅为试验材料,通过人工栽植和修剪的方法分别得到不同密度和不同生长高度的高羊茅,并通过统一变量的方法测定其不同情况的高羊茅在冲刷流量下的冲刷深度,最后通过曲线拟合,确定冲刷深度与高羊茅的栽植密度和生长高度之间的相关关系。同时,对含有不同密度高羊茅的土体进行颗粒分析试验,测定土体中含有不同级配颗粒的含量,通过曲线拟合,得出土体中所含不同粒级的颗粒质量百分比与冲刷流量之间的相关关系。结果表明:在株高相同的情况下,土体的冲刷深度随着高羊茅密度的增大而减小,冲刷深度与高羊茅密度呈现出对数增长趋势;在密度相同的情况下,与株高为0cm的高羊茅土体相比较,植株高度为18cm时,对土壤冲刷深度的减少作用为46.11%;株高为12cm时,对土壤冲刷深度的减少作用为43.65%;株高为6cm时,对土壤冲刷深度的减少作用为41.40%。在株高相同的情况下,不含高羊茅的土体,其冲刷深度随着冲刷时间呈现了线性关系,而含有不同密度的高羊茅土体冲刷深度随着冲刷时间呈现了对数关系。在相同的冲刷流量下,植草密度越大,其土体中所含颗粒的质量百分比相对越稳定。

In order to determined the effect of planting grass on the characters of soil anti-scouring under the circumstance in the open channel bottom tank, tall fescue, the most popular grass for slope protection in Liaoning province, was planted. Different densities and heights of tall fescue were tested respectively by artificial planting and the pruning. The scour depth of tall fescue under different scouring flows was measured. From the curve fitting, the relationship between scour flows and tall fescue of different planting densities and heights was observed. The soil particle analysis was carried out with different densities of tall fescue. The content of different gradation particles in soil was determined through the curve fitting; the relationship between the different grade of quality percentage in soil particles and scouring depth was also determined. Results showed that the scouring flows were inversely proportional to plant heights under the condition of the same plant height. The densities of tall fescue and scour depth presented a logarithmic growth trend along with the time. Under the same planting density, compared with the control, plant height of 18 cm reduced soil erosion depth by 46.11%, plant height of 12 cm reduced by 43.65%, and plant height of 6 cm reduced by 41.40%. Under the same planting density, the scour depth increased with the increasing heights of tall fescue, gradually tended to a stable state. The increased density of tall fescue enhanced the character of soil anti-scouring,making the content of the soil particles to be more stable. It concluded that under the same scouring flow, the greater the density of planting grass the more relatively stable the quality percentage of soil particles contained.