植物护坡土坝过水试验研究

Experiment on Overflowing the Earth Dam Protected by Vegetation on Dam Slopes

洪水漫顶是土质淤地坝垮坝的主要原因之一。为研究淤地坝超防洪标准的保坝措施,山西省水保所进行了植物护坡土坝过水试验研究。试验坝坝高6米、下游坝坡1:2.5,栽植野牛草、羊草、紫穗槐、拧条护坡,经堰顶水深0.38～0.56米溢流,护坡植物都表现出具有增强坝坡抗冲能力的作用,其中野牛草护坡经70多分钟溢流,坝坡才开始形成局部冲坑。在护坡植物中,禾本科草本植物明显优于柠条、紫穗槐等灌木,野牛草好于羊草。试验研究表明,对群众性的小型淤地坝,采用植物护坡防止非常洪水漫顶造成的垮坝是经济可行的。本文论述了植物护坡过水试验情况及流态变化,并对护坡植物的抗冲性能进行了研究分析。

Overtopping is one of the major cause for failure of silt arresting earth dams.In the study of protecting measures for the silt arrester of which the designed standard of flood prevention is exceeded,the Soil and Water Conservation Institute of Shanxi Province made an experiment of planting vegetation on dam slopes to prevent the dam from failure by overtopping. The height of the experimental dam is 6 m and the downstream slope is 1:2.5. Buffalograss, sheepgrass (Aneurolepidium chinense), shrubby falseindigo and Chinese peashrub are planted on sloping surface of the dam for protection against the overflow. The erosion resistant ability of the dam slope is enhanced by planting these plants, when the water with a depth of 0.38-0.56 m overflows the top of dam,local scour holes begin to form on the dam slope covered by buffalograss after overflowing for more than 70 min.By comparison,it is found that the grass family vegetation is more advantageous than shrubs such as shrubby falseindigo, Chinese peashrub and and others,and buffalograss is better than sheepgrass when these plants are used for protecting the dam slope.The experiment shows that in order to prevent the dam from failure due to overtoping by abnormal flood,it is feasible to protect the bam slope with plants in small size silt arresting dams.The paper describes the experiment and the variation of flow pattern and analyses the erosion-resistant ability of the protection plants.