植被混凝土边坡抗冲刷模型对比试验研究
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摘要
植被混凝土是岩质边坡生态防护的主要技术手段.针对目前植被混凝土边坡抗冲刷性能研究不足,本文通过自主设计的边坡坡面冲刷试验车及人工降雨装置,进行包括1∶0.75、1∶1和1∶1.25等3个不同边坡坡度,1.9、2.4和2.9 L/min等3个不同降雨强度,素土边坡和植被混凝土边坡等2种不同边坡防护形式在内的共计18组室内人工降雨冲刷模拟试验,每组试验降雨历时60 min,每10 min记录一次泥沙侵蚀数据.对比分析了植被混凝土边坡在雨水冲刷作用下坡面的侵蚀过程,统计了不同试验条件下的泥沙侵蚀量,同时基于能量法进行了理论推导与计算,针对植被混凝土边坡提出等效糙率概念对公式进行了修正.试验结果表明:植被混凝土边坡泥沙侵蚀量远小于素土边坡,说明其在施工初期就能具备良好的抗冲刷性能;植被混凝土边坡坡面侵蚀主要为层状面蚀,存在局部的细沟侵蚀,素土边坡坡面侵蚀呈现出明显的沟蚀;素土边坡和植被混凝土边坡的泥沙侵蚀量与降雨强度和坡度均呈正相关关系,试验过程中,没有出现临界坡度并分析了原因;基于能量法的理论计算能较好适应素土边坡,植被混凝土边坡泥沙侵蚀量的计算在通过提出等效粗率的方法后,理论值与试验值较为接近,但存在一定误差,如何合理减小误差及探讨其中的理论联系还需要进一步的深入研究.
Vegetation concrete is the main technical means for the ecological protection of rock slope. In view of the shortage of current research on the anti-scour performance of vegetation concrete slope, three different slopes with slope rates of 1:0.75, 1:1, and 1:1.25 were tested using an independently designed slope scouring test car and an artificial rainfall device. A total of 18 indoor artificial rainfall scouring simulation tests were conducted with three different rainfall intensities(i.e., 1.9, 2.4, and 2.9 L/min) and two different forms of slope protection(i.e., plain soil and vegetation concrete slopes). The rainfall in each group lasted 60 min, and the sediment erosion data were recorded every 10 min. The erosion process of vegetation concrete slope under the action of rainfall scouring was compared and analyzed, and the amount of sediment erosion under different test conditions was counted. At the same time, the theoretical derivation and calculation were conducted on the basis of the energy method, and the concept of equivalent roughness was proposed for the vegetation concrete slope, with which the formula was modified. Test results show that the sediment erosion of vegetation concrete slope was much smaller than that of plain soil slope, indicating that the vegetation concrete slope exhibited a satisfying anti-scour performance even at the beginning of construction. The slope erosion of vegetation concrete slope was mainly layered surface erosion with local rill erosion, whereas that of plain soil slope was mainly gully erosion. The sediment erosion of both slopes was positively correlated with rainfall intensity and slope rate. No critical slope rate was observed during the tests, the reason for which was also analyzed. The theoretical calculation based on the energy method can be better adapted to the plain soil slope. After the introduction of the proposed equivalent roughness, the theoretical value of the sediment erosion amount of vegetation concrete slope was closer to its experimental value. However, there existed certain errors, and how to reasonably reduce the errors and explore the theoretical connection therein still needs further research.
Vegetation concrete is the main technical means for the ecological protection of rock slope. In view of the shortage of current research on the anti-scour performance of vegetation concrete slope, three different slopes with slope rates of 1:0.75, 1:1, and 1:1.25 were tested using an independently designed slope scouring test car and an artificial rainfall device. A total of 18 indoor artificial rainfall scouring simulation tests were conducted with three different rainfall intensities(i.e., 1.9, 2.4, and 2.9 L/min) and two different forms of slope protection(i.e., plain soil and vegetation concrete slopes). The rainfall in each group lasted 60 min, and the sediment erosion data were recorded every 10 min. The erosion process of vegetation concrete slope under the action of rainfall scouring was compared and analyzed, and the amount of sediment erosion under different test conditions was counted. At the same time, the theoretical derivation and calculation were conducted on the basis of the energy method, and the concept of equivalent roughness was proposed for the vegetation concrete slope, with which the formula was modified. Test results show that the sediment erosion of vegetation concrete slope was much smaller than that of plain soil slope, indicating that the vegetation concrete slope exhibited a satisfying anti-scour performance even at the beginning of construction. The slope erosion of vegetation concrete slope was mainly layered surface erosion with local rill erosion, whereas that of plain soil slope was mainly gully erosion. The sediment erosion of both slopes was positively correlated with rainfall intensity and slope rate. No critical slope rate was observed during the tests, the reason for which was also analyzed. The theoretical calculation based on the energy method can be better adapted to the plain soil slope. After the introduction of the proposed equivalent roughness, the theoretical value of the sediment erosion amount of vegetation concrete slope was closer to its experimental value. However, there existed certain errors, and how to reasonably reduce the errors and explore the theoretical connection therein still needs further research.
引文
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[8]刘青泉,陈力,李家春.坡度对坡面土壤侵蚀的影响分析[J].应用数学和力学,2001,22(5):449-457.Liu Qingquan,Chen Li,Li Jiachun.Influences of slope gradient on soil erosion[J].Applied Mathematics and Mechanics,2001,22(5):449-457(in Chinese).
[9]Horton R E.Erosional development of streams and their drainage basins;hydrophysical approach to quantitative morphology[J].Geological Society of America Bulletin,1945,56(3):275-370.
[10]李志刚,张新宇.基于能量法的土工构造物边坡冲刷量计算模型研究[J].土木工程学报,2005,38(6):122-124,136.Li Zhigang,Zhang Xinyu.A energy-based erosion calculation model of the slopes for civil ergineering structures[J].China Civil Engineering Journal,2005,38(6):122-124,136(in Chinese).
[2]李锁平,石敬华.植被混凝土植草技术在石质边坡防护中的应用[J].路基工程,2004(5):47-49.Li Suoping,Shi Jinghua.Application of vegetation concrete planting technique for rock side slope protection[J].Subgrade Engineering,2004(5):47-49(in Chinese).
[3]刘大翔,李少丽,许文年,等.植被混凝土有机质类型与配比的合理选取[J].水利水电科技进展,2012,32(4):37-40,54.Liu Daxiang,Li Shaoli,Xu Wennian,et al.Selection tests for type and ratio of organic matter in vegetation concrete[J].Advances in Scienc and Technology of Water Resources,2012,32(4):37-40,54(in Chinese).
[4]杨奇,丁瑜,许文年,等.植被混凝土抗雨水冲刷性能试验研究[J].中国水土保持,2013(1):54-56.Yang Qi,Ding Yu,Xu Wennian,et al.Experimental study on the resistance of vegetation concrete to rain water scour[J].Soil and Water Conservation in China,2013(1):54-56(in Chinese).
[5]中华人民共和国住房和城乡建设部.GB 50014-2006室外排水设计规范[S].北京:中国计划出版社,2016.Ministry of Housing and Urban-Rural Development of China.GB 50014-2006 Code for Design of Outdoor Wastewater Engineering[S].Beijing:China Planning Press,2016(in Chinese).
[6]夏振尧,许文年,王乐华.植被混凝土生态护坡基材初期强度特性研究[J].岩土力学,2011,32(6):1719-1724.Xia Zhenyao,Xu Wennian,Wang Lehua.Research on characteristics of early strength of ecological slopeprotected base material of vegetation-growing concrete[J].Rock and Soil Mechanics,2011,32(6):1719-1724(in Chinese).
[7]Zingg A W.Degree and length of land slope as it affects soil loss in run-off[J].Agric Engng,1940,21:59-64.
[8]刘青泉,陈力,李家春.坡度对坡面土壤侵蚀的影响分析[J].应用数学和力学,2001,22(5):449-457.Liu Qingquan,Chen Li,Li Jiachun.Influences of slope gradient on soil erosion[J].Applied Mathematics and Mechanics,2001,22(5):449-457(in Chinese).
[9]Horton R E.Erosional development of streams and their drainage basins;hydrophysical approach to quantitative morphology[J].Geological Society of America Bulletin,1945,56(3):275-370.
[10]李志刚,张新宇.基于能量法的土工构造物边坡冲刷量计算模型研究[J].土木工程学报,2005,38(6):122-124,136.Li Zhigang,Zhang Xinyu.A energy-based erosion calculation model of the slopes for civil ergineering structures[J].China Civil Engineering Journal,2005,38(6):122-124,136(in Chinese).