Suffusion Sensitivity of Earth-fill Dam soils in Korea through Seepage Tests

Suffusion;Internal erosion;Internal stability;Suffusion test;Fill dam materials;Failure mode;Grain-size distribution;624

University:서울대학교 대학원

关键词: Suffusion;    Internal erosion;    Internal stability;    Suffusion test;    Fill dam materials;    Failure mode;    Grain-size distribution;    624;   

Others  :  http://s-space.snu.ac.kr/bitstream/10371/160979/1/000000158320.pdf

美国|英语

来源: Seoul National University Open Repository

【 摘 要 】

In Korea, most of the dams are fill dams, which is made of ground material decomposed from rocks, mostly granite. Such hydraulic earth structures can undergo different kinds of damages and result in several failuremodes. Among these, internal erosion, overtopping and slope instability are the major possible failure modes. From the dam failure cases abroad, it is shown that internal erosion turned out to be the most responsible failure mode that can lead to a dam breach. Suffusion is the process by which finer soil particles are moved through constrictions between larger soil particles by seepage forces and it is the phenomenon responsible for internal erosion. If suffusion takes place, the permeability of the soil will change sharply, and this can induce a reduction of the shear strength. It can also lead to clogging by the fine particles in the downstream side of the dam and can develop excessive pore pressure causing slope instability or render the filter less effective in protecting the core materials. The phenomenon of suffusion has been studied by a number of researchers and based on the analysis of laboratory suffusion test results they have proposed criteria on grain size distribution to evaluate the internal stability of the soils. The suffusion test conducted by several researchers, however, are different in terms of the testing methods. Such discrepancies in suffusion test methods lead to the problem of applicability of the existing criteria on dams. Therefore, the means of applying the criteria in evaluating the internal stability of domestic dams is insufficient, and the surest method is to conduct a laboratory suffusion test together with the consideration of influential factors of the tests.In this study, the existing criteria for assessing the internal stability of the soils are introduced and applied to 9 different domestic fill dam materials. Suffusion tests are conducted on well-graded silty-sand, which has a representative grain size distribution of earth-fill dams in Korea. Based on the test results, suffusion sensitivity is evaluated. The influential factors are also considered and evaluated.