Review and Improvement Direction of the Riprap Design Standard for Fill Dams in Korea

摘要

Since domestic reservoirs are mainly soil-fill dams, slope protection measures are necessary to prevent erosion, weathering, and wave-induced loss of soil, and riprap is the most common slope protection method. Although design standards for riprap at fill dams are provided in National Design Standard of Korea, they use out-of-date criteria based largely on overseas standards that may not be applicable to the Korean context. This study aimed to identify problems with the current design standards by comparing them with overseas standards, and to suggest directions for improving Korean standards through investigations of existing embankments. The review found that domestic design standards restrict the quality and maximum particle size of stone used for riprap. Much of the design criteria are based on past surveys of the performance record for fill dams conducted by the US Army Corps of Engineers. So this can be unsuitable for changes in modern technology and environmental conditions in Korea. More recent design trends suggest riprap size using an experimental formula, which is numerically different from the data presented in domestic design standards, and this may lead to unstable and uneconomic dams. In addition, various factors such as the shape, weight, and gradation of the riprap can also have a strong influence on riprap stability. The results of the survey show that current condition of the riprap protection is different from the domestic design standard, but it is judged that the stability is satisfied with the overseas design standards. In the field survey, 12 sites were selected in consideration of regional distribution. The results of the survey show that current condition of the riprap protection is different from the domestic design standard, but it is judged that the stability is satisfied with the overseas design standards.