• 제목/요약/키워드: 웰 포인트

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슈퍼웰포인트공법에 의한 고진공배수 압밀탈수에 대한 시공사례 (Research for a cases of overseas constructions and domestic tentative execution about high vacuum dewatering and consolidation/dehydration by Super Well point method)

  • 신창범;김대활;시게요시 다카하시;이광열
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2008년도 추계 학술발표회
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    • pp.581-590
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    • 2008
  • A SWP method is a revolutionary dewatering method. The conventional dewatering method, deep-well method, had ever occurred a civil appeal caused by the well depletion in compliance with the reduction of the groundwater level over a wider area considerably by the deep-well pumping from homogeneous sand-layer ground for a dry-work, while pump groung excavation working in Sendai city, Japan 10 years ago. it'd developed with the problematic proposal to find the new method which can lower the groundwater level only within the sheet pile without any reduction of groundwater outside of the sheet pile and until currently steady improvement came. It's been confirmed with plenty of executional results that there was almost no decreasing of water-level from surroundings, over so many construction-sites including vertical shafts which completely does not enter into non-water permeable layer and pumping ground etc. The SWP method in this time has been introducing initially and carried into a the execution tentatively at a construction-site and made a various result get through the execution.

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A12024-T4의 프레팅 피로균열거동에 관한 실험적 연구 (An experimental study on the fretting fatigue crack behaviour of A12024-T4)

  • 이봉훈;이순복
    • 대한기계학회논문집A
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    • 제21권3호
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    • pp.511-518
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    • 1997
  • The technique of fretting fatigue test was developed and fretting fatigue tests of A12024-T4 were conducted under several conditions. The newly developed calibration methods for measuring surface contact tractions showed good linearity and repeatability. The plate type specimen to which tow bridge type pads were attached and vision system was used to observe the crack behaviour. The oblieque cracks appeared in the early stage of crack growth and they became mode I cracks as they grow about 1 mm. The mode I transition points were found to be longer when surface tractions are higher or bulk stress is lower. Before the crack becomes mode I crack, 'well point' where crack grow about rate is minimum, was detected under every experimental condition. The crack behaviour was found to be affected by surface tractions, contact area, bulk stress. It was also found that partial slip and stick condition is most detrimental and the crack starts from the boundary of stick and slip. For gross slip crack started at the outside edge of pad. After crack mode transition, fretting fatigue cracks showed almost same behaviour of plain mode I fatigue cracks. Equivalent stress intensity factor was used to analyze the behaviour of fretting fatigue cracks and it was found that stress intensity factors can be applied to fretting fatigue cracks.