• Title, Summary, Keyword: Seepage flow

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Development of the Seepage flow Monitoring Method by the Hydraulic Head Loss Rate on Sea Dike (수두손실률에 의한 방조제 침투류 감시기법 개발)

  • Eam, Sung-Hoon;Yoon, Chang-Jin;Kim, Seong-Pil;Heo, Jun;Kang, Byung-Yoon
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.60-68
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    • 2010
  • In this study, the seepage flow monitoring method by hydaulic head loss rate graph was developed for the purpose of monitoring the seepage flow from the see side or from the lake on sea dike in which seepage force was varied periodically. The hydraulic head loss rate was defined in this method. The value of the rate is in the range from 0 to 1. the value of 0 means perfectly free flow of seepage. the value of 1 means perfect waterproofing. The value of coefficient of determination in the hydraulic head loss rate graph closer to 1 means that the seepage flow way is stable. The value of coefficient of determination in the hydraulic head loss rate graph closer to 0 means that the hole may exist or the piping may be in the progress. The pore water pressure data measured in Saemangeum sea dike was analyzed with the developed method The result showed that the variation of seepage flow state was detected sensitively by this method and the interception effect of sea dike could be estimated quantitatively.

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Friction Factor of Seepage Flow (투수층흐름에서의 마찰계수)

  • 유동훈;권순국
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.6 no.4
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    • pp.397-403
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    • 1994
  • The seepage flow has been investigated conducting laboratory experiments mainly in order to determine the relation of seepage flow friction factor against Reynolds number. The apparatus of seepage flow measurements has the water flow almost horizontaly. Several sets of experiments were carried out, and various flow conditions were obtained in each set of flow. To cover wide range of flow conditions, used were various materials of different measurement sizes and various stages of water discharge in the seepage flow tests. Shape factor equation was developed using existing data, and based on the present laboratory data, an explicit equation was developed for the estimation of friction factor of seepage flow in the range of Reynolds number from about 1 to about 600. The same equation is expected for the flow condition of Reynolds number over 600, considering the trend of friction factor distribution.

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A Study on Seepage Characteristics in Case of Seaward Seepage Through Sea-dike (역경사 현태를 가진 방조제 성토층 단명에서의 침출현상 연구)

  • Hong, Byung-Man
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.40 no.5
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    • pp.43-51
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    • 1998
  • In design and management of sea0dikes, engineers need to study various transient seepage conditions through dikes not only for the sea water infiltration into dikes due to cyclic rises of sea water level also for the seepage flow out from dikes toward the sea due to cyclic drawdown of sea water level. Characteristics of seepage flow toward the sea from dikes are more complicated than as known and remained unclearly. The case of such seepage flow may be explained by figuring out seepage characteristics in filter as a part of sea-dikes. Filters in most sea-dikes in Korea are inevitably placed with reversely inclined shape due to field construction conditions. Most computer programs for seepage analysis based on the various numerical methods give practically acceptable results, but for the case of reversely inclined section of filters any verification to apply them might be needed. In this study, large scaled model tests were executed to verify and understand seepage flow through earth-filled sea-dikes. The results from numerical analysis and model tests show some remarkable differences in pore pressure distribution under cyclic changes of see level, and some of the results need to be considered in design and construction practices with further study.

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Experimental Study on Seepage Losses in Earth Channel (흙 수로에 대한 삼수손실량 추정에 관한 실험적 연구)

  • 정하우;유한열
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.15 no.1
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    • pp.2853-2877
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    • 1973
  • Models of cross-sections and channels were made in order to measure seepage losses. Cross-sections were made of sand, sandy clay loam and loam, their thicknesses being 30cm and 40cm, respectively. Flow depths kept in the cross-sections were 4cm, 6cm, 8cm and 10cm. Straight and curved channel models were provided so as to measure seepage losses, when constant water depths maintained at the heads of the channels were 7.3cm and 5.7cm, respectively. The results obtained in this experiment are presented as follows: 1) A cumulative seepage loss per unit length at a point in the channel varies in accordance with time and flow depth. The general equation of cumulative seepage loss may be as follows(Ref. to Table V.25): $$q_{cum}=\int_{o}^aq(a)dt+\int_a^bq(b)dt+\int_b^tq(c)dt$$ 2) In case that the variation of water depth through the channel is slight, the total seepage loss may be computed by applying the following general equation: $$\={q}_{cum}{\cdot}x=\int_o^tq_{cum}\frac{{\partial}x}{{\partial}t}dt$$ 3) Because seepage loss varies considerably according to water depth in case that the variation of flow depth through the channel is great, seepage loss should be computed by taking account of the change of flow depth. 4) The relation between time and traveling distance of water flow may be presented as the following general equation(Ref. to Table V.29): $$x=pt^r$$ 5) The ratios of the seepage losses of the straight channel to the curved channel are 1:1.03 for a flow depth of 7.3cm and 1:1.068 for that of 5.7cm. 6) The ratios of the seepage losses occurring through the bottom to those through the inclined plane in the channel cross-section are 1:2.24 for a water depth of 8cm and 1:2.47 for a depth of 10cm in case that soil-layer is 30cm in thickness. Similarly, those ratios are 1:2.62 and 1:2.93 in case of a soil-layer thickness of 40cm(Ref. to Table V.5).

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Variation of Seepage Line through Embankments by Permeability of Layer (지반의 투수성에 따른 제체 침투류의 변화)

  • 신진환;이봉직
    • Journal of the Korean Society of Safety
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    • v.11 no.2
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    • pp.109-115
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    • 1996
  • The movement of water through a river embankment and its influenced upon the stability of the slope of the embankment are described. The stability of the embankment is depended upon the location of seepage line. As the seepage flow occurs in the embankment, the slope of the embankment loses its stability. Of particular interest is the stability following a rapid change of water level. The variation of seepage line in the embankment model by a fluctuation of water level is discussed. The experimental models were construction with slopes of 1 : 1.5, 1 : 2.0, 1 : 2.5 and the flow velocity was turned from 60cm/sec~90cm/sec. Based on the experimental study, the following conclusions are drawn. 1) When water level is raised, the seepage line of downstream slope Is raised rapidly as flow velocity increases. 2) For the case of permeable layer, the seepage line raised rapidly as compare with impermeable layer when water lever is raised.

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Development of the Seepage Flow Monitoring Method by the Hydraulic Head Loss Rate (수두손실률에 의한 침투류 감시기법 개발)

  • Eam, Sung-Hoon;Kang, Byung-Yoon;Kim, Ki-Wan;Koo, Ja-Ho;Kang, Shin-Ik;Cha, Hung-Youn;Jung, Jae-Hyun;Cho, Jun-Ho;Kim, Ki-Soo
    • Journal of the Korean Geotechnical Society
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    • v.26 no.5
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    • pp.37-48
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    • 2010
  • In this study, the seepage flow monitoring method by the hydraulic head loss rate was developed for the purpose of application to offshore construction site enclosed by cofferdams in which seepage force varies periodically. The amount of the hydraulic head loss rate newly defined in this graph was in a range between 0 and 1. The zero of the rate means the existence of flow with no seepage resistance. The 1 of the rate means no seepage flow through the ground. The closer to 1 the coefficient of determinant in the hydraulic head loss graph is, the more the ground through which seepage water flows is stable. The closer to 0 the coefficient of determinant in the hydraulic head loss graph is, the more the ground through which seepage water flows was unstable and the higher the possibilities of existence of empty space or of occurrence of piping on the seepage flow pass in the ground is. The hydraulic head loss graph makes it possible to monitor sensitively the situation of seepage flow state, and the graph helps to understand easily the seepage flow state at the specific section on the whole cofferdam.

Study on the Permeability of Concrete under Water Pressure (수압을 받는 콘크리트의 투수성에 관한 연구)

  • You, Jo-Hyeong;Lee, Han-Seung
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.719-722
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    • 2005
  • The watertightness of concrete is judged by the depth of penetration of water forced in under pressure with the mechanism of flow of seepage water examined theoretically and experimentally. As a result, it is found that in the case of low water pressure approximately 0.15Mpa or less, the flow is Darcy seepage flow, the same as flow in an ordinary sand stratum, whereas in the case of high water pressure, the flow is diffused seepage flow accompanied by internal deformation of concrete. It is suggested that the watertightness of concrete be evaluated by seepage coefficient in the case of the former and diffusion coefficient in the case of the latter.

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An Experimental Study of Non-Steady State Seepage in the Levee Model by Parallel Water Flow (수평흐름에 의한 제방모형내의 비정상침투에 관한 실험적 연구)

  • Shin, Bang Woong;Lee, Bong Jik
    • Journal of The Korean Society of Civil Engineers
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    • v.14 no.5
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    • pp.1253-1263
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    • 1994
  • The stability of the embankment is depended upon the location of seepage line. As the seepage flow occurs in the embankment, the slope of the embankment loses its stability. Of particular interest is the stability following a rapid change of embankment level. The variation of seepage line in the embankment model according to flow velocity was investigated. In addition to this non-steady state flow in embankment by a fluctuation of water level is discussed. The experimental model was construction with slopes of 1 : 2.5 and flow velocity is turned from 60 cm/sec~90 cm/sec. Analysis of the experimental results, the seepage line is influenced by flow velocity and coefficient of permeability.

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Studies on Seepage Flow Analysis through Sea Dike (防潮堤의 浸透流 解析에 관한 硏究)

  • Kim, Gwan-Jin;Jo, Byeong-Jin;Yun, Chung-Seop
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.34 no.1
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    • pp.87-99
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    • 1992
  • A mathematical model, UNSATR which predicts the seepage flow through the body of dike especially under the tidal fluctuation has been developed. This model has been revised from UNSAT2 model which was developed on the basis of the saturated-unsaturated theory by Neuman. UNSATR has been verified and applied to the hydraulic model in order to estimated the seepage quantity, the formation of free water surface etc. The results lead to the following conclusions : 1. Seepage rates between the mathematical model and hydraulic model experiment are very similar to each other both in constant and transient water level conditions. 2. The lapsed time to be steady state of the free water surface becomes late as the tidal levels are relatively low mainly due to the seepage flow from the unsaturated zone of the body of dike. 3. Under the transient state of water levels, owing to the flow from the unsaturated domain, streamlines crossing to the free water surface are found and time lag during a falling tide may allow the free water surface inside the body of dike to stand at a high level than the outside water level. 4. The utility and validity of UNSATR model are convinced when the analyses on seepage problems through the porous embankment of the soil structures on the conditions of the steady and unsteady states are carried out.

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Effect of Wave-Induced Seepage on the Stability of the Rubble Mound Breakwater (동적 파랑에 의한 침투류가 사석경사식 방파구조물의 안정성에 미치는 영향)

  • Hwang, Woong-Ki;Kim, Tae-Hyung;Kim, Do-Sam;Oh, Myounghak;Park, Jun-Young
    • Journal of the Korean Geotechnical Society
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    • v.34 no.3
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    • pp.13-27
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    • 2018
  • To study how stable the rubble mound breakwaters are, one can look to the research of wave induced seepage flow through the pores of the rubble mound. Seepage flow is generally generated by the difference between the water level around the breakwater during a typhoon. The existing stability analysis method of the rubble mound is the static analysis which simply considers the force equilibrium taking into account the horizontal force acting on the concrete block induced by a wave (calculated by Goda equation) and the vertical force induced by the weight inclusive of the concrete block, quarry run, filter, and armor layer above the slipping plane. However, this static method does not consider the wave-induced seepage flow in the rubble mound. Such seepage may decrease the stability of the rubble mound. The stability of a rubble mound breakwater under the action of seepage was studied based on the results of CFD software (OpenFOAM) and Limit Equilibrium Method (GeoStudio). The numerical analysis result showed that the seepage flow decreased the stability of the rubble mound breakwaters. The results of the numerical analyses also revealed the stability of the rubble mound was varied with time. Especially, the most critical state happened at the condition of overtopping the concrete block, acting strong uplift pressure raising along side and underneath the concrete block, and generating high pore pressure inside rubble mound due to seepage flow. Therefore, it may be necessary to conduct a dynamic analysis considering the effect of wave-induce seepage flow together with the static analysis.