• Title/Summary/Keyword: Pier scour

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Riprap Scour Countermeasures around Nonuniform Bridge Piers (불균일단면교각 주위의 사석 세굴 보호공)

  • Yun, Tae-Hun;Park, Gi-Du
    • Journal of Korea Water Resources Association
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    • v.33 no.4
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    • pp.385-392
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    • 2000
  • An experimental investigation was conducted to determine the effect of a nonuniform pier on the stability of riprap placed around bridge piers. A nonuniform pier is one of which the cross-sectional dimension varies over the length of the pier and comprises a cylinder of diameter bp placed on a larger diameter of foundation bf. and the stability of riprap are significantly influenced by the height of foundation z. The critical height of foundation is defined as the height of foundation which has the same critical velocity to that of uniform pier without foundation, and it was found to be zc=0.8bf. For z

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New measuring method for the scour and the water level by temperature measurement (온도계측을 통한 교량 세굴 및 수위 측정방법)

  • Joo, Bong-Chul;Park, Ki-Tae;Hwang, Yoon-Koog
    • Proceedings of the Korea Concrete Institute Conference
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    • 2009.05a
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    • pp.553-554
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    • 2009
  • This paper introduces the new measuring method for the water level and the scour. The method measures temperature between water and ground by temperature sensors. It analyzes the change of temperature. It estimates the water level and the ground level, and calculates the scour. If the temperature sensors installed until the top of the pier, it can measure the water level.

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A formula for the Decision of the Riprap Size for the Local Scour Protection around Bridge Piers (교각주위 국부세굴 방지를 위한 사석크기 결정 공식)

  • Choe, Gye-Un;Kim, Hyeon-Tae;An, Gyeong-Su
    • Journal of Korea Water Resources Association
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    • v.34 no.6
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    • pp.753-761
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    • 2001
  • In this paper, the experiments to decide the riprap size for the local scour protection at bridge piers and the coefficients of attack angle were conducted. A formula for the decision of the riprap size and a figure for the coefficients of attack angle were suggested based upon the experimental results. The coefficients of attack angle indicate different values based on the variation of the length-width ratio of bridge pier and the coefficients are increased by the increment of the attack angle. In this paper, the experiments using the piers having the opening ratios of 90%, 92.86% and 95% were conducted. Also, the attack angles 0$^{\circ}$, 15$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$ and 60$^{\circ}$ as well as four different length-width ratios of the bridge pier were utilized. The suggested formula were compared with 6 different formulas and the riprap sizes calculated using the equation suggested in this paper indicate the similar patterns with the formula suggested by Richardson. The suggested formula in this paper can be widely applied in the riprap design for the local scour protection around the bridge pier with the consideration of the attack angle to the flow.

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Experimental Study on Scouring Range according to Bridge Pier Shape (교각형상에 따른 국부세굴범위에 대한 실험 연구)

  • Lee, Kap-Yong;Choi, Sung-Nyung;Choi, Sung-Wook;Park, Moo-Jong
    • 한국방재학회:학술대회논문집
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    • 2008.02a
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    • pp.477-480
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    • 2008
  • Hydraulic experiment was executed to identify the souring range of bride pier. The experiment categorized three kind of bridge pier shape, that is composed of circle shape, square shape and the special shape. Measured scouring data was compared with the results by empirical CSU formula which was generally used in practice. As empirical formula could not consider backfill, measured scouring range is by far smaller than results of CSU formula. Therefore in case of design anti-scouring structure, there is the possibility of overestimation in case of using empirical formula.

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Unsteady Flow Analysis for the Design of Local Scour Protection by HEC-RAS(UNET) Model in the River Reach Affected by Tide (HEC-RAS 모형에 의한 감조하천구간 부정류 해석 및 세굴보호공 설계)

  • Namgung, Don;Cho, Doo-Chan;Yoon, Kwang-Seok
    • Proceedings of the Korea Water Resources Association Conference
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    • 2005.05b
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    • pp.1138-1142
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    • 2005
  • The tidal river is a river affected by tide, which causes the water level to rise and fall two times everyday periodically. The local velocity across the river could be very fast because of the cross-sectional characteristics of the river even though it's not a rainy season. Therefore extreme local scour could take place around hydraulic structures such as piers and caissons due to backward flow velocity. For the construction of pier foundation of Ilsan-bridge In the Han River, the field observations were performed to get the velocity and water level. The numerical analysis was performed by HEC-RAS(UNET). The relationship between measured maximum velocity and calculated mean velocity is achieved, which is used to estimate the velocity and water level as the construction is proceeding. Countermeasures for scour were designed with the results of the hydraulic analysis to avoid potential damage during construction work. According to the results of monitoring, the velocity increase after temporary road embankment was negligible, from which it is considered that the degradation of main channel compensated for the constriction of cross-section by embankment.

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Field Evaluation of Scour Countermeasure Using Geobag (지오백 세굴보호공법의 현장 적용성 평가)

  • Park, Jae-Hyun;Kwak, Ki-Seok;Lee, Ju-Hyung;Chung, Moon-Kyung
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.1251-1258
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    • 2006
  • Field evaluation of new scour countermeasure using geobag and aggregate is performed to prepare for the basis of design and construction standard in Korea. Polyester non-woven geotextile is determined as a geobag material and tire cord is used to sew up the geobag which contain aggregate. Hwasang-gyo(bridge) is selected as a pilot test site through office review and field investigation. According to the design flood of Hwasang-gyo(bridge), the size and volume of geobag are calculated and construction area and required number of geobags are computed by considering the specification of the pier and foundation of the bridge. After construction, scour depth around geobag construction area is measured and the stability of geobag is ascertained by using pole and digital camera.

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A study on the applicability of system for monitoring the flood level and the scour at railroad bridge (철도교량 홍수위감시 및 세굴검지 시스템 적용성 고찰)

  • Park Young Kon;Lee Jin Wook;Yoon Hee Taek;Kim Seon Jong
    • Proceedings of the KSR Conference
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    • 2005.05a
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    • pp.530-535
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    • 2005
  • To monitor the flood level under heavy rainfall and the scour at railroad bridge, the system, which can effectively collect, store and transmit the data, is developed and applied to the field. The results in this study are as follows. 1) Monitoring for water level and scour depth is well done in view of the recording velocity and the accuracy of data which are measured. 2) This system is based on the web, internet and it is able to collect the realtime data and to analyze the risk. 3) When water level excesses the limit of danger level of a river on which railroad bridge is located, or when scour depth and angle of inclination of pier is increased, the scenario for early warning signal which sends to managers at central traffic control and drivers of trains is automatically made. It is judged that this system secures the safety of railroad and protects lives of train passengers as the warning signal sends to running train in advance at risky situation of railroad bridge under heavy rainfall.

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Response Dominant Frequency Analysis for Scour Safety Evaluation of Railroad Piers (철도 교각의 세굴 안정성 평가를 위한 응답 지배주파수 분석)

  • Jung, Hyun-Seok;Lee, Myungjae;Yoo, Mintaek;Lee, Il-Wha
    • Journal of the Korean Geotechnical Society
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    • v.36 no.11
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    • pp.83-95
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    • 2020
  • In order to evaluate the stability of the geo-structure of railway bridge, the response dominant frequency was analyzed based on a series of impact vibration load test results. The specifications of the experiment piers were obtained by referring to the completion design data, and when data was missing, a field study was conducted. The impact vibrations test according to the scouring progress was carried out at one pier scheduled to be abandoned, and it was confirmed that the response dominant frequency can be utilized as an evaluation index for scour. In addition, the response dominant frequency was measured through an impact load test at 46 piers in 5 bridges in operation, and the scour safety of the bridge was evaluated by comparing it with the japanese proposal formula.