• Title/Summary/Keyword: reservoir stability

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The Analysis of the Slope Stability for the Small Dam (Small Dam의 斜面安定 解析)

  • Choi, Ki-Bong;Bae, Woo-Soek
    • Journal of the Korean Society of Safety
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    • v.19 no.2
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    • pp.88-92
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    • 2004
  • The paper decribes a procedure for the evaluation of the effect of seepage force on stability of slopes. The stability of an embankment impounding a water reservoir is highly depend upon the location of seepage line with the embankment. To evaluate the accurate safety factor of an embankment, it is important to illustrate the seepage phenomenon. Of particular interest is the stability following a rapid change of reservoir level. Seepage forces in embankments are easily determined interest is the stability following a rapid change of resrvoir level. Seepage forces in embankments are easily detemined if frictional forces are expressed in relation to hydraulic gradient I. If a piezometer is inserted into a body of embankment, the level to which fee water rises is a measure of the energy at that point.

The Theoritical Analysis of the Slope Stability subjected to Seepage Force (침투력을 고려한 사면안정의 이론적 해석)

  • Gi-Bong Choi
    • Journal of the Korean Society of Safety
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    • v.11 no.4
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    • pp.151-155
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    • 1996
  • The main purpose of this study was to develop a useful method for analysing slope stability by seepage force. The stability of an embankment impounding a water reservoir is highly depend upon the location of seepage line with the embankment, it is important to illustrate the seepage phenomenon. Of particular interest is the stability following a rapid rise change of reservoir level. Seepage forces in embankments are easily determined if frictional forces are expressed in relation to hydraulic gradient i. Seepage forces can combine with soil weights to improve stability or worsen it, depending on the direction in which the forces act ;n relation to the geometric cross section.

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Seepage Characteristics of Agricultural Reservoir Embankment Considering Filter Interval (필터간격을 고려한 농업용저수지 제체의 침투특성)

  • Lee, Young Hak;Lee, Dal Won
    • Journal of The Korean Society of Agricultural Engineers
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    • v.60 no.1
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    • pp.1-10
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    • 2018
  • This study analyzed pore water pressure, seepage and leakage quantity, height of seepage and critical hydraulic gradient in order to suggest the seepage characteristics of agricultural reservoir embankment considering filter interval. The seepage characteristics of a deteriorated reservoir embankments were conducted according to the horizontal filter intervals range using three- dimensional finite element analysis. The wider the horizontal filter interval, the higher the pore water pressure increased, and the pore water pressure ratio in the center of the core has a greater effect than the base part. The seepage and leakage quantity appeared largely in the two-dimensional analysis conditions (case 1), where the filter was constructed totally in the longitudinal direction of the embankment, the wider the horizontal filter interval was gradually reduced. The reasonable filter intervals to yield efficient seepage characteristics were within 30 m for the pore water pressure of the core and the height of the seepage line. The stability of the filter installation was able to evaluate the stability of the piping by the critical hydraulic gradient method. The deteriorated reservoir with no filters or decreased functionality can significantly reduce the possibility of piping by simply installing a filter on the downstream slope. In the future, the deteriorated reservoir embankment should be checked for the reservoir remodeling because the core and filter functions have been lost or decreased significantly. In the case of a new installation, the seepage characteristic behavior due to the core and filter changes should be applied to the field after obtaining a reasonable horizontal filter interval that satisfies the safety factor by a three-dimensional analysis.

Prediction of Compaction, Strength Characteristics for Reservoir Soil Using Portable Static Cone Penetration Test (휴대용 정적 콘 관입시험을 통한 저수지 제방 토양의 다짐, 강도 특성 및 사면 안정성 예측)

  • Jeon, Jihun;Son, Younghwan;Kim, Taejin;Jo, Sangbeom;Jung, Seungjoo;Heo, Jun;Bong, Taeho;Kim, Donggeun
    • Journal of The Korean Society of Agricultural Engineers
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    • v.65 no.5
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    • pp.1-11
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    • 2023
  • Due to climate change and aging of reservoirs, damage to embankment slopes is increasing. However, the safety diagnosis of the reservoir slope is mainly conducted by visual observation, and the time and economic cost are formidable to apply soil mechanical tests and slope stability analysis. Accordingly, this study presented a predicting method for the compaction and strength characteristics of the reservoir embankment soil using a portable static cone penetration test. The predicted items consisted of dry density, cohesion, and internal friction angle, which are the main factors of slope stability analysis. Portable static cone penetration tests were performed at 19 reservoir sites, and prediction equations were constructed from the correlation between penetration resistance data and test results of soil samples. The predicted dry density and strength parameters showed a correlation with test results between R2 0.40 and 0.93, and it was found to replace the test results well when used as input data for slope stability analysis (R2 0.8134 or more, RMSE 0.0320 or less). In addition, the prediction equations for the minimum safety factor of the slope were presented using the penetration resistance and gradient. As a result of comparing the predicted safety factor with the analysis results, R2 0.5125, RMSE 0.0382 in coarse-grained soil, R2 0.4182 and RMSE 0.0628 in fine-grained soil. The results of this study can be used as a way to improve the existing slope safety diagnosis method, and are expected to be used to predict the characteristics of various soils and inspect slopes.

Beam stability improvement of a liquid metal ion source (액체 금속 이온원의 빔 안정도 향상)

  • 현정우;임연찬;김성수;박철우;이종항;강승언
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.04a
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    • pp.504-507
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    • 2004
  • Previous studies on the liquid Gallium ion sources used an electro-chemically etched tungsten wire with a coil-type heater. Such a structure requires excessive power consumption in the course of heating the liquid metal. In this work, a new structure is proposed that replaces the coil-type heater. It uses a Gallium reservoir made of six pre-etched 250 $\mu\textrm{m}$ tungsten wires that surround the needle electrode. Gallium loading at the reservoir is observed to be much more stable, resulting in an improved beam stability.

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Beam stability improvement of liquid metal ion source (액체 금속 이온원의 빔 안정도 향상)

  • Hyun J. W.;Yim Youn Chan;Kim Seuong Soo;Oh Hyun Joo;Park Cheol Woo;Lee Jong Hang;Choi Eun Ha;Seo Yunho;Kang Seung Oun
    • Journal of the Korean Vacuum Society
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    • v.13 no.4
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    • pp.182-188
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    • 2004
  • Previous studies on the liquid Gallium ion sources used an electro-chemically etched tungsten wire with a coil-type heater. Such a structure requires excessive power consumption in the course of heating the liquid metal. In this work, a new structure is proposed that replaces the coil-type heater. It uses a Gallium reservoir made of six pre-etched 250$\mu\textrm{m}$ tungsten wires that surround the needle electrode. Gallium trading at the reservoir is observed to be much more stable, resulting in an improved beam stability.

Non-uniform wind environment in mountainous terrain and aerostatic stability of a bridge

  • Chen, Xingyu;Guo, Junjie;Tang, Haojun;Li, Yongle;Wang, Lei
    • Wind and Structures
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    • v.30 no.6
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    • pp.649-662
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    • 2020
  • The existence of a dam has potential effects on the surrounding wind environment especially when it is located in mountainous areas. In this situation, the long-span bridge over the reservoir can easily be exposed to non-uniform incoming flows, affecting its wind-resistance performance. This paper presents a study on the aerostatic stability of such a bridge. Wind tunnel tests were first carried out to investigate the wind environment above a mountainous reservoir. The results show that the angle of attack and the wind speed along the bridge axis show obvious non-uniform characteristics, which is related to the inflow direction. When winds come from the south where the river is winding, the angle of attack varies along the span direction significantly. The finite element model for the bridge was established using ANSYS software, and effects of non-uniform wind loads on the aerostatic stability were computed. Non-uniform angle of attack and wind speed are unfavorable to the aerostatic stability of the bridge, especially the former. When the combined action of non-uniform angle of attack and wind speed is considered, the critical wind speed of aerostatic instability is further reduced. Moreover, the aerostatic stability of the bridge is closely related to the dam height.

The Analysis of the Slope Stability in Embankment(I) (제체의 사면안정 해석(I))

  • 최기봉
    • Journal of the Korean Society of Safety
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    • v.12 no.4
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    • pp.134-142
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    • 1997
  • The stability of an embankment Impounding a water reservoir is highly depend upon the location of seepage line with the embankment. To evaluate the accurate safety factor of an embankment, it is important to illustrate the seepage phenomenon. Of particular interest is the stability following a rapid change (drawdown) of reservoir level Seepage forces in embankments are easily determined if frictional forces are expressed in relation to hydraulic gradient Ⅰ. If a piezometer is inserted into a body of embankment, the level to which free water rises is a measure of the energy at that point. From model test result, it is possible to calculate safety factors of earth embankment. To assure the validity of this research, tests were conducted with numerical experimental models. And the experiment models were constructed with slopes of 1:1.0, 1:1.5, 1:2.0, 1:2.5. Analysis of experimental results, seepage force was analyzed according to downstream time, internal friction angle and cohesion, respectively.

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A Study on the Stability of Intake gate in a Dam (취수문비의 안정성에 관한 연구)

  • Kwack, Young-Kyun;Ko, Sung-Ho;Kang, Min-Koo
    • The KSFM Journal of Fluid Machinery
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    • v.11 no.1
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    • pp.46-51
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    • 2008
  • A stability analysis has been made for a newly designed gate of intake tower of reservoir. The analysis is composed of finding the natural frequency of the gate and the frequency induced by water flowing over and through the gate. ANSYS is employed to calculate the natural frequency of the gate and SC/Tetra is utilized for calculating flow field around the gate, which in turn gives the frequency of pressure force fluctuation on the gate. In addition to the safety analysis, the present study presents how the gate selectively intakes a muddy water layer located in the middle depth of reservoir.

An Experimental Study on Overflow and Internal Erosion Protection Technology of a Reservoir (저수지 제체월류 및 내부침식 보호기술 모형실험 연구)

  • Jin, Ji-Huan;Lee, Tae-Ho;Yoo, Jeon-Yong;Im, Eun-Sang;Lee, Seung-Joo;Kim, Yong-Seong
    • Journal of the Korean Geosynthetics Society
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    • v.18 no.4
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    • pp.181-191
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    • 2019
  • Most of the reservoirs in South Korea are fill dam, and overflow and piping phenomena have been detected as the main causes of failure of fill dam. In this study, an operating ◯◯ reservoir located in Gongju-si is modeled in centrifuge model test to study the behavior of reservoir during water level rise and overflow conditions. In order to simulate seepage and overflow in the real reservoir, the model was constructed in 1/50 scale, and deteriorated and reinforced conduits were installed. After modeling the reinforced and deteriorated conditions of the conduits, LVDTs, pore pressure gauges were installed and centrifuge model tests were carried out with water level rise and overflow conditions in order to analyze the reservoir behavior according to the reinforcement methods. The results of centrifuge model test in water level rise condition show that deteriorated conduit has adverse effects in the stability of the reservoir body, and the conduit which is reinforced by the inverse lining method has enhanced stability of the reservoir body. Moreover, installation of water spillway is seen to prevent the scour and erosion of the reservoir body. The study provides a basic data required for the reinforcement of conduit and water spillway in the reservoir.