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2024 Vol.40, Issue 4 Preview Page
Behavior of Monopile for Offshore Wind Turbine in Loose Silty Sand under Lateral Cyclic Loading via Centrifuge Model Test

원심모형실험을 활용한 느슨한 실트질 모래지반에서 해상풍력 모노파일의 반복수평하중에 대한 거동 평가

Jae-Kweon Lee1
,
Sung-Min Yun2
,
Young-Jin Jeon3
,
Jae-Hyun Kim4*
이 제권1
,
윤 성민2
,
전 영진3
,
김 재현4*
1Member, Graduate Student, Dept. of Intergrated Energy and Infrasystem, Kangwon National Univ.
2Member, Graduate Student, Dept. of Civil Engineering, Kangwon National Univ.
3Senior Researcher, Institute of Industrial Technology, Kangwon National Univ.
4Member, Assistant Prof., Dept. of Civil Engineering, Kangwon National Univ.
1정회원, 강원대학교 에너지인프라융합학과 석사과정
2정회원, 강원대학교 토목공학과 석사과정
3비회원, 강원대학교 산업기술연구소 선임연구원
4정회원, 강원대학교 토목공학과 조교수
*Corresponding Author
31 August 2024. pp. 33-47
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Abstract

Offshore wind structures are subject to long-term repeated horizontal loads from wind, waves, and currents, making it essential to consider these loads in the design of offshore foundations. In this respect, monopiles are large-diameter hollow steel pipes that are relatively simple to construct compared with piles used on onshore sites. They can provide stable support for wind structures and have well-established design codes, leading to their widespread use globally. The behavior of monopiles under lateral static loads is typically assessed using the p-y method proposed by the American Petroleum Institute (API). However, the applicability of p-y curves to large-diameter monopiles exposed to repeated cyclic horizontal loads, such as those experienced in offshore wind applications, must yet be evaluated. Thus, this study evaluated the behavior of monopiles under two-way cyclic horizontal loads in loose silty sand, a representative soil type of the southwestern coast of Korea, using centrifuge model tests. The results demostrated that the behavior of monopiles varied depending on the loading level, number of cycles, and direction of the cyclic loads. Furthermore, the p-y curve method proposed by the API overestimated the behavior of a large-diameter monopile installed in silty sand under two-way cyclic loads.

Keywords
Centrifuge
Cyclic load
Monopile
Offshore wind turbine
p-y curve
Silty sand

해상풍력 구조물은 파랑, 바람, 조류 등에 의한 반복수평하중에 장기적으로 노출되기 때문에 기초구조물 설계 시 이에 대한 고려가 필수적이다. 모노파일(monopile)은 일반적으로 육상에서 사용하는 말뚝에 비해 직경이 큰 중공형 강관으로 설계법이 잘 정립되어 있으며 시공이 비교적 단순하고, 안정적으로 풍력 구조물을 지지할 수 있는 장점이 있어 전 세계적으로 널리 활용되고 있다. 해상풍력 모노파일의 횡방향 정적하중에 대한 거동 평가는 American Petroleum Institute(API)에서 제안하는 p-y 곡선법을 활용하는데, 해상풍력과 같이 반복수평하중에 장기간 노출되는 경우 대구경 모노파일에 대한 p-y 곡선법의 적용성을 평가할 필요가 있다. 본 연구에서는 국내 서남해안 지역의 대표지반 중 하나인 느슨한 실트질 모래지반에서 양방향(two-way) 반복수평하중을 받는 모노파일의 거동을 원심모형실험을 통해 평가하였다. 그 결과, 모노파일의 거동은 반복하중 크기, 반복하중 횟수, 반복하중의 방향에 따라 달라지는 것을 확인하였다. 또한, API에서 제시하는 p-y 곡선법이 대구경 모노파일의 양방향 반복수평하중에 대한 거동을 과대평가하고 있음을 확인하였다.

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Information
  • Publisher :The Korean Geotechnical Society
  • Publisher(Ko) :한국지반공학회
  • Journal Title :Journal of the Korean Geotechnical Society
  • Journal Title(Ko) :한국지반공학회 논문집
  • Volume : 40
  • No :4
  • Pages :33-47
  • Received Date : 2024-05-31
  • Revised Date : 2024-07-18
  • Accepted Date : 2024-07-22
  • DOI :https://doi.org/10.7843/kgs.2024.40.4.33
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