• 제목/요약/키워드: Scouring

검색결과 230건 처리시간 0.026초

Reliability considerations in bridge pier scouring

  • Muzzammil, M.;Siddiqui, N.A.;Siddiqui, A.F.
    • Structural Engineering and Mechanics
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    • 제28권1호
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    • pp.1-18
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    • 2008
  • The conventional design of bridge piers against scour uses scour equations which involve number of uncertain flow, sediments and structural parameters. The inherent high uncertainties in these parameters suggest that the reliability of piers must be assessed to ensure desirable safety of bridges against scour. In the present study, a procedure for the reliability assessment of bridge piers, installed in main and flood channels, against scour has been presented. To study the influence of various random variables on piers' reliability sensitivity analysis has been carried out. To incorporate the reliability in the evaluation of safety factor, a simplified relationship between safety factor and reliability index has been proposed. Effects of clear water (flood channel) and live bed scour (main channel) are highlighted on pier reliability. In addition to these, an attempt has also been made to explain the failure of Black mount bridge of New Zealand based on its pier's reliability analysis. Some parametric studies have also been included to obtain the results of practical interest.

빙쇄굴 모델에 의한 극지 해저 파이프라인의 매설깊이 산정 (Estimation of burial depth for arctic offshore pipelines by an ice scour model)

  • 윤기영;최경식
    • 한국해양공학회지
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    • 제11권2호
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    • pp.1-10
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    • 1997
  • The interaction of ground ice features with underlying seabed is one of the major considerations in the design of Arctic pipeline systems. Regarding the development of offshore gas field near Sakhalin Island, which is an ice-infested area, in this paper an ice scour model to determine the burial depth of Arctic offshore pipeline is studied. Using a simplified ice-seabed interaction process, ice scour depth is easily estimated. This nonlinear numerical model can simulate the scouring process for various enviromental parameters such as ice mass, incoming velocity, soil strength. This study also deals with interaction forces during the scouring process in sloping seabed conditions and discusses the ice loads that are transmitted through the seabed soil.

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Design of Ship Thruster and Seabed Scouring due to Effects of Water Velocity

  • Choi, Byoung-Yeol;Lee, Sang-Gil
    • Journal of Advanced Research in Ocean Engineering
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    • 제3권3호
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    • pp.102-111
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    • 2017
  • This study considered the effects on the seabed of a harbor and quay wall from ship maneuvers in relation to the thruster jet flow and initial velocity. This study also included the engine capacity, RPM, and diameter and pitch of a ship's thruster for a required speed. The impact of a scour hole on the environment of a quay wall was investigated. Based on these results, a risk based analysis was conducted to evaluate different strategies and their consequences. There has been an increase in the loads on the bottom of a harbor during ship maneuvering. This increase is caused by the propeller loads of mooring and unmooring vessels. This indicates a greater number of arrivals and departures of vessels with larger drafts, larger thruster diameters, and larger available thruster power capacities. Another important cause could be an increase in the maneuverability of vessels from the use of bow thrusters. The increasing loads, which cause a higher jet flow above the bottom, can lead to undesirable scour holes.

직기 특성이 PET직물 물성에 미치는 영향(II) (Effects of Weaving Machine Characteristics on the Physical Properties of PET Fabrics (II))

  • 김승진;손준혁;강지만;박명환
    • 한국염색가공학회지
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    • 제16권4호
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    • pp.36-44
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    • 2004
  • This research surveys the differences of fabric mechanical properties according to the different looms and the fabric positions with relation to warp and weft weaving tensions on the Picanol and Omega looms respectively. For this purpose, the grey fabrics woven in the previous paper are processed in dyeing and finishing processes, and the processing shrinkages are measured on each processes such as dryer, scouring, pre-set, dyeing and final-set using the fabric density and width. The mechanical properties of the finished fabrics are measured and discussed with relation to the warp and weft weaving tensions of the two looms and the variations of the fabric mechanical properties according to the fabric positions are also discussed. In addition, the fabric thickness according to the fabric positions such as right, left selvedges and center of the fabrics is also measured and discussed with the characteristics of the Picanol and Omega looms.

실트샌드 지반상 사석호안 축조시 원지반의 세굴대책에 관한 연구 (Study on Scour Countermeasures during Revetment Construction in Silty Sand Soil Layers)

  • 양태선;안중선;조영구;지태균;김희동
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2006년도 춘계 학술발표회 논문집
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    • pp.322-329
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    • 2006
  • On the way of construction in harbor area, scourin problems took place slowly failure of embankment in the beginning of construction in sites. For studying on the scouring properties during revetment construction in silty sand soil layers, this paper is carried out on lessons of case studies of numerical seepage analysis, scouring countermeasures in dredged landfill area.

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A Parametric Study on Ice Scouring Mechanism for Determination of Pipeline Burial Depths

  • Park, Kyung-Sik;Lee, Jong-Ho
    • Journal of Ship and Ocean Technology
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    • 제8권2호
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    • pp.29-40
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    • 2004
  • Interaction of grounded ice ridges with underlying seabed is one of the major considerations in the design of Arctic pipeline system. Previously several ice scour models were developed by researchers to describe the ice scour-seabed interaction mechanism. In this paper, a parametric study on ice scouring mechanism is performed and the limitation of ice scour-seabed interaction models is discussed. Simple laboratory tests are carried out and then the shape pattern of deposited soil around the ice is redefined. New ice scour model assumes trapezoidal cross section based on the field observation data. Ice scour depth and soil resistance forces on seabed are calculated with varying the keel angle of a model ice ridge.

전해환원수에 의한 폴리에스테르 직물의 감량가공 특성 (Weight Reduction Properties of PET Fabrics Treated with Electrolytic Reduction Water)

  • 노덕길;홍영기;배기서
    • 한국염색가공학회지
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    • 제17권5호
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    • pp.37-44
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    • 2005
  • The electrolytic water(EW) has been used in agriculture, medical, semiconductor, and household fields. However there has been no use of EW in the textile process so far, because the application in the textile industry has been needed a large amount of EW in real process conditions. Recently, we have got electrolytic oxidation water(EOW) and electrolytic reduction water(ERW) by development of a electricity electron technology. And, the productivity of EW manufacture apparatus is arrived to large capacity. As a result, the application of EW could be possible in the textile industry. In this study, to confirm the possibility of application of EW, we scoured and hydrolyzed PET fabric using the EW. It was possible that the application of ERW for the scouring and hydrolysis of PET fabrics in the textile process.

연성 식생모형에 의한 해빈침식방지 특성에 관한 실험적 연구 (Hydraulic Experiment on the Effects of Beach Erosion Prevention with Flexible Coastal Vegetation)

  • 이성대;박정철;홍창배
    • 한국해양공학회지
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    • 제23권1호
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    • pp.31-37
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    • 2009
  • Coastal vegetation consists of rooted flowering marine plants that provide a variety of ecosystem services to the coastal areas they colonize. The attenuation of currents and waves and sediment stabilization are often listed among these services. From this point of view, artificial seaweed is an effective method of controlling sea bed sediment and stabilization without damaging the landscape or the stability of the coastline. A series of hydraulic experiments were performed in a wave channel with regular and irregular waves to examine the effect of artificial seaweed in relation to scouring and beach erosion prevention. Based on the results of these experiments, the coastal vegetation model is efficient against scouring and beach erosion.