工程堆积体坡面植物篱的减流减沙效益及其机理研究

发布时间：2018-05-31 19:08

本文选题：工程堆积体 + 植物篱　；参考：《中国科学院研究生院（教育部水土保持与生态环境研究中心）》2015年硕士论文

【摘要】：生产建设项目在施工及生产过程中会产生大量工程堆积体,而堆积体的土壤侵蚀模数远高于自然坡面,极易产生严重的水土流失,为探索工程堆积体水土保持的有效措施,本研究利用宽5m,长20m的标准径流小区,通过野外模拟径流试验,在24°、28°、32°三种坡度下,采用35L/min、45 L/min、55L/min三种放水流量,研究了工程堆积体坡面应用植物篱措施后的侵蚀过程、减流减沙效益及其侵蚀动力机理,并分析了其控蚀能力的时序变化。得到了以下结论:(1)对照小区和植物篱小区的产流量、产沙量都随着小区坡度和放水流量的增加而增大,植物篱可以有效减少径流量和侵蚀量:①减流效益介于4%~40%之间,并随着小区坡度的增加而增大,但与径流流量不是简单的正相关关系,随着流量的增加先增大后减小。②减沙效益介于15%~45%之间,随着坡度和放水流量的增加而减小。(2)对照小区和植物篱小区的产流率、产沙率均随坡度和放水流量的增加而增大;随冲刷历时的推移,产流率在前期迅速增大而后趋于平稳,产沙率在前期快速上升,之后明显下降,在大流量(45、55L/min)下,冲刷末段超过了初始时段;植物篱小区的产流率小于对照小区,且植物篱小区的产流时刻比对照小区要滞后2~10min,冲刷后期二者的产沙率逐渐接近甚至前者超过后者。(3)对照小区和植物篱小区的细沟侵蚀量在区段1(0~6m)内所占比例最高(≥40%),随着坡度增加,坡面上部(0~10m)沟蚀量所占的比例呈现先增加后减小的趋势,随着流量的增加,坡面下部(10~20m)所占的比例随之增大,细沟向下发育的更加完善。植物篱对坡面下部防护作用较好,将细沟侵蚀限制在上部坡面,且对24°和32°坡面的沟蚀分布影响较大。(4)随着放水流量和坡度的增加,对照小区侵蚀泥沙中砂粒的含量逐渐增加,黏粒含量减少;相对于对照小区,植物篱可以减弱侵蚀过程中径流对砂粒的剥蚀和搬运;分形维数可以作为植物篱对侵蚀产沙中泥沙颗粒粒级分布的评价指标。(5)植物篱将坡面剥蚀率从3~10g·m-2·s-1降低到1.5~8g·m-2·s-1,剪切力从4~8N·m-2降低到2.5~6N·m-2,将临界剪切力和临界功率分别提高了0.25倍和5倍,植物篱通过降低坡面径流能量,削弱径流侵蚀动力,提高坡面的抗侵蚀能力,减小了水流对坡面的剥蚀程度。(6)植物篱的控蚀能力随着径流冲刷历时的延长存在临界值,二者之间可用二次函数进行较好拟合,累积减沙量的最大值出现在冲刷历时26min之后,且随坡度和流量的增加而提前;径流含沙量的时序变化是植物篱控蚀能力存在时间限制的直接原因;分析实际含沙量与径流挟沙能力变化可以发现植物篱与坡面径流输沙的源~汇关系,是控蚀能力存在临界值的深层原因。
[Abstract]:In the process of construction and production, a large amount of Engineering accumulation will be produced in the process of construction and production, and the soil erosion modulus of accumulation is far higher than that of the natural slope. It is very easy to produce serious soil erosion. In order to explore the effective measures for soil and water conservation of the engineering accumulation body, this study uses a standard runoff plot with wide 5M and long 20m, through field simulated runoff test, Under the 24 degrees, 28 degrees and 32 degrees three kinds of slope, 35L/min, 45 L/min and 55L/min three kinds of discharge flow were used to study the erosion process, the benefit of sediment reduction and erosion dynamic mechanism after the application of hedgerow measures on the slope surface of the engineering accumulation body, and the time series of its erosion control ability were analyzed. The following conclusions were obtained: (1) the production of the control area and the plant hedgerow district. The flow rate and sediment yield increase with the increase of slope and discharge flow, and the hedgerow can effectively reduce the runoff and erosion. (1) the benefit of the dewatering is between 4%~40%, and increases with the increase of the slope of the plot, but it is not a simple positive correlation with the runoff flow, and it increases first and then decreases with the increase of the flow rate. Between 15%~45%, with the increase of slope and discharge flow, (2) the yield rate of the control area and the hedgerow area increased with the increase of the slope and the discharge flow, and the rate of yield increased rapidly in the early stage and then tended to smooth with the passing of the scour. In 45,55L/min, the last section of the scour was more than the initial period; the yield rate of the hedgerow plot was less than the control area, and the flow time of the hedgerow plot was 2~10min lagged behind the control area, and the rate of sediment yield of the two late scour was closer to the former than the latter. (3) the rill erosion of the control area and the hedgerow area was 1 (0~6 M) has the highest proportion (> 40%). With the increase of the slope, the proportion of the upper (0~10m) gully erosion is increasing first and then decreasing, with the increase of the flow rate, the proportion of the lower part of the slope (10~20m) increases and the rill is more perfect downward. The hedge against the lower slope is better, and the rill erosion is limited to the rill erosion. On the upper slope, the distribution of gully erosion in the 24 and 32 degrees slope has great influence. (4) with the increase of the discharge flow and the slope, the content of sand grains in the erosion sediment in the control area is increased gradually and the content of the clay particles is reduced. The hedge can weaken the erosion and transport of the sand grains in the erosion process. (5) the hedgerow reduced the erosion rate from 3~10g. M-2. S-1 to 1.5~8g. M-2. S-1. The shear force decreased from 4~8N. M-2 to 2.5~6N m-2. The critical shear force and critical power were increased by 0.25 times and 5 times respectively. The hedgerow reduced the runoff energy and weakened the runoff invasion by reducing the runoff energy. Erosion power, increase the erosion resistance of slope and reduce the erosion degree of water flow to slope. (6) the control ability of hedgerow has a critical value along with the extension of runoff scouring, and the two can be fitted well with two functions. The maximum amount of cumulative sediment reduction occurs after the scouring period of 26min, with the increase of slope and flow. In advance, the temporal variation of runoff sediment concentration is the direct reason for the time limit of the hedgerow control erosion ability. The analysis of the actual sediment concentration and the change of sediment carrying capacity can find the source and sink relationship between the hedgerow and the runoff sediment transport, which is the deep reason for the critical value of the erosion control ability.
【学位授予单位】：中国科学院研究生院（教育部水土保持与生态环境研究中心）
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157.4

【引证文献】