모래지반에 설치된 병렬식 그룹석션앵커의 인발하중에 대한 수치해석 연구

김수린 ( Su Rin Kim ),추연욱 ( Yun Wook Choo ),권오순 ( O Soon Kwon ),김동수 ( Dong Soo Kim ) 한국현대언어학회 2014 언어연구 Vol.30 No.3

본 연구에서는 수치해석을 이용하여 모래지반에 설치된 병렬식 그룹석션앵커의 인발하중에 대한 거동을 분석하였다. 단일형과 병렬식 그룹석션 앵커에 대한 수치 모델을 구성하고 인발하중을 재하하여 하중재하점의 위치, 길이/직경비, 하중경사 및 단위앵커간 간격에 따른 그룹형 석션앵커의 인발지지력에 대한 영향을 연구하였다. 더블형과 트리플그룹앵커의 인발지지력은 단일앵커의 인발지지력 대비 1.7배와 2.4배로 나타났고, 설치간격이 증가함에 따라 그 증가율은 증가하였다. 하중재하점, 하중경사, 단위앵커의 형상비의 차이는 그룹앵커의 인발저항력 증가비에 큰 영향을주지 않는 것으로 나타났다. In this study, the performance of group suction anchors installed in sand and subjected to pullout loading was investigated by numerical analysis. The group suction anchors consist of two or three units rigidly connected to each other in parallel array and the pullout resistances were compared with that of a single anchor. Parametric study was performed using numerical models to study the effect of the physical conditions of the group anchor. The parameters include the skirt length to diameter ratio of a unit suction anchor, the pad-eye location, inclination of loading and the spacing between unit suction anchors. The analysis shows that the ratios of the pullout capacity of double suction anchor and triple suction anchor to that of single anchor are 1.7 and 2.4, respectively. The ratio increases with the increase in the spacing between the unit anchors. The other parameters such as the skirt length to the diameter ratio, the location of the pad-eye and the loading inclination have negligible effect on the ratio of pullout resistances of the group anchor to the single anchor.

사질토 지반에서 경사 인발 하중을 받는 석션 앵커의 회전 거동 평가

배준식,정영훈 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.10

Suction anchors are used for floating structures because they have advantages in installation and stability. Recently, the demand for floating structures requiring low allowable displacement has increased. Thus, it is strongly suggested that the displacement of the suction anchor be evaluated. However, conventional studies regarding suction anchors have concentrated on the capacity of the anchor, and research on the displacement of the anchor is limited. In particular, rotation is the primary behavior of a suction anchor subjected to an inclined load, and related information has been insufficient. Therefore, the main objective of this paper is to investigate the rotation behavior of a suction anchor via centrifuge model tests. The experimental parameters are the inclination of the pull-out load, anchor dimensions, and aspect ratio. The rotation values of suction anchors were compared using a series of load-rotation curves. The results show that the inclination of the load has a dominant influence on the rotation behavior of the suction anchor. 석션 앵커는 비교적 간편한 설치 방식과 높은 안정성으로 인해 부유식 구조물을 고정하기 위한 기초로 사용된다. 최근, 허용 변위가 작은 부유식 구조물이 증가함에 따라, 석션 앵커의 유발 변위 평가에 대한 수요가 높아졌다. 하지만, 기존 석션 앵커의 연구는 앵커 지지력 평가에 초점을 두었으며, 앵커의 변위에 관한 연구는 중점적으로 수행되지 않았다. 특히, 경사진 하중을 받는 석션 앵커의 주된 변위인, 회전 거동을 평가한 연구는 매우 부족한 실정이다. 따라서 본 논문에서는 경사 인발 하중이 작용하는 석션 앵커의 회전 거동을 모형실험을 통해 비교 및 분석 하였다. 모형실험은 센트리퓨지 실험 장비를 사용하였으며, 실험 변수로는 하중의 경사도, 앵커의 크기 및 종횡비가 고려되었다. 하중-회전 변위 곡선을 산정하여, 실험 변수에 따른 석션 앵커의 회전량을 비교하였다. 실험 결과, 석션 앵커의 회전 거동은 하중의 경사도에 큰 영향을 받았으며, 앵커의 크기 및 종횡비에 따른 회전량의 차이는 크지 않았다.

Analytical study of the failure mode and pullout capacity of suction anchors in clay

Liu, Haixiao,Wang, Chen,Zhao, Yanbing Techno-Press 2013 Ocean systems engineering Vol.3 No.2

Suction anchors are widely adopted in mooring systems. However there are still challenges in predicting the failure mode and ultimate pullout capacity of the anchor. Previously published methods for predicting the inclined pullout capacity of suction anchors are mainly based on experimental data or the FEM analysis. In the present work, an analytical method that is capable of predicting the failure mode and ultimate pullout capacity of the suction anchor in clay under inclined loading is developed. This method is based on a rational mechanical model for suction anchors and the knowledge of the mechanism that the anchor fails in seabed soils. In order to examine the analytical model, the failure angle and pullout capacity of suction anchors from FEM simulation, numerical solution and laboratory tests in uniform and linear cohesive soils are employed to compare with the theoretical predictions and the agreement is satisfactory. An analytical method that can evaluate the optimal position of the attachment point is also proposed in the present study. The present work proves that the failure mode and pullout capacity of suction anchors can be reasonably determined by the developed analytical method.

Analytical study of the failure mode and pullout capacity of suction anchors in sand

Liu, Haixiao,Peng, Jinsong,Zhao, Yanbing Techno-Press 2015 Ocean systems engineering Vol.5 No.4

Suction anchors are widely adopted and play an important role in mooring systems. However, how to reliably predict the failure mode and ultimate pullout capacity of the anchor in sand, especially by an easy-to-use theoretical method, is still a great challenge. Existing methods for predicting the inclined pullout capacity of suction anchors in sand are mainly based on experiments or finite element analysis. In the present work, based on a rational mechanical model for suction anchors and the failure mechanism of the anchor in the seabed, an analytical model is developed which can predict the failure mode and ultimate pullout capacity of suction anchors in sand under inclined loading. Detailed parametric analysis is performed to explore the effects of different parameters on the failure mode and ultimate pullout capacity of the anchor. To examine the present model, the results from experiments and finite element analysis are employed to compare with the theoretical predictions, and a general agreement is obtained. An analytical method that can evaluate the optimal position of the attachment point is also proposed in the present study. The present work demonstrates that the failure mode and pullout capacity of suction anchors in sand can be easily and reasonably predicted by the theoretical model, which might be a useful supplement to the experimental and numerical methods in analyzing the behavior of suction anchors.

Uplift Capacity of a Plate Anchor Considering Suction Effects

YOUNG-KYO SEO,TAE-HYUNG KIM 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.6

Anchors have been commonly used to as foundation systems of the structures that require the uplift resistance. Recently anchors have been used in ocean sediment for mooring systems to stabilizeoffshore structures. In the saturated clayey soil however, suction developed between the soil and anchor and affects the uplift capacity of anchor. To estimate the uplift capacity of the anchor accurately, the failure mechanisms of the anchor by the uplift force should also be correctly assumed. The uplift capacity is usually expressed in terms of breakout factors with respect to embedment ratio. In this paper, a two-dimensional plane strain numerical investigation into the vertical uplift capacity of a plate anchor in a clayey soil is described. The breakout factor against their corresponding values of embedment ratio was calculated and plotted along a single curve. The modes of failure mechanism at shallow and deep anchors are also presented.

단일벽 및 이중벽 모형앵커를 이용한 석션케이슨 앵커의 거동분석

김유석,안재훈,Kim. Yusuk,Teodosio. Bertrand,Ahn. Jaehun 한국방재학회 2014 한국방재학회논문집 Vol.14 No.2

풍력발전은 신재생 에너지 중 가장 유망하다고 판단되는 에너지 중 하나이다. 심해에서는 부유식 풍력발전기가 가장 경제적인 것으로 평가받고 있으며, 이에 따라 부유식 해상풍력발전기에 대한 연구가 세계적으로 활발하게 진행되고 있다. 해상풍력발전기의 개발에는 부유체를 해양지반에 고정하는 앵커의 개발이 필수적이며, 석션케이슨 앵커는 현재까지 가장 널리 쓰이는 해양앵커 중 하나이다. 본 논문은 모형실험을 통해 카올리나이트 점토지반에 관입된 석션케이슨 앵커의 수직인발력을 분석하고, 수직인발력으로부터 점토와 앵커 사이의 마찰계수와 앵커의 선단 역지지계수를 산정한다. 산정된 마찰계수와 역지지계수는 기존의 문헌들의 결과와는 유사한 경향을 보이나, 현재 설계에 적용되는 값들보다는 다소 작은 값을 나타낸다. 따라서, 본 모형실험장비는 해양앵커의 정성적 거동을 해석하는데 더 적절한 것으로 판단된다. 향후, 본 논문의 결과를 바탕으로 반복하중 하 석션케이슨 앵커의 거동 계측을 통해 해양환경에서 앵커의 영구변형을 산정하기 위한 연구를 이어 진행할 예정이다. Wind power presently reflects a very promising source of renewable energy. The optimal type of foundations for offshore wind turbines, in very deep water, is the floating type; the research on floating wind turbines is very active worldwide. It is essential to develop anchoring system for floating structures, and the suction caisson anchor is one of most widerly used in deep oceans. This paper addresses the anchor holding capacity of suction caisson anchors under vertical pull-out, and friction and reverse end bearing coefficients based on mode tests. The values of friction and reverse end bearing coefficients put in similar ranges with literature values, but are still lower than those suggested in design guides. It is, therefore, suggested the current model tests may predict qualitative trends of suction caission anchors` behaviors. As subsequential works, based on current results, it is planned to conduct cyclic tests to estimate the permanent behavior of anchors under oceanic environments.

천해역 점성토 지반에 적합한 오탁방지막 기초 앵커

권기철(GI-CHUL KWEON),홍남식(NAM-SEEG HONG),송무효(MU-HYO SONG),최창규(CHANG-GYU CHOI) 한국해양공학회 2003 韓國海洋工學會誌 Vol.17 No.3

The Navy has tested the holding capacity of many kinds of anchors in order to propose the design chart for the holding capacity of drag-embedment anchors. The design chart is only applicable up to the cable bottom angle 6° when load is raised to the ultimate weight. However, the anchor experiences a significant uplift force when the angle is above 6° in shallow seas. In this paper, the procedure for the estimation of the holding capacity of anchors in mud is proposed. Drag-embedment anchors do not function well when there is a significant uplift component of load in soft seafloor materials, such as mud. Under these loading and seafloor conditions, gravity anchors seems to be more efficient. However, they are too heavy for their holding capacity. Therefore, suction pile (hollow concrete block) is more beneficial to the foundation of silt protector in shallow sea with mud seafloor materials.

침투해석을 이용한 석션 케이슨에 작용하는 외력 평가

김정수(Kim, Jeongsoo),정연주(Jeong, Yeon-Ju),박민수(Park, Min-Su) 대한토목학회 2019 대한토목학회논문집 Vol.39 No.2

석션 케이슨은 설치 수심제한이 적고, 비교적 단순한 설치공정과 빠른 시공이 가능하기 때문에 해양 구조물용 앵커 및 기초형식으로 활용되고 있으며 그 적용이 점차 확대되고 있다. 석션 케이슨 기초의 설계는 지반의 지지력 및 안정성 검토가 중심이 되며, 관련 설계기준에서 해석 방법을 제시하고 있다. 반면, 케이슨의 구조적 안전성 분석은 방법이 정형화되지 않았으며 특히 케이슨에 작용하는 하중 모델링에 대한 명확한 산정 방법이 정립되지 않아 석션 케이슨 단면 설계에 어려움이 있다. 이러한 이유로 본 연구에서는 이론 및 수치적 침투해석을 통해 석션압에 의해 발생되는 케이슨 내외부의 간극수압 크기 및 분포를 분석하고, 이를 바탕으로 구조해석에 적용할 수 있는 합리적인 하중 평가 방법을 제시하였다. 추가적으로 관입깊이, 투수계수의 이방성, 석션압 변화가 내외벽에 작용하는 간극수압에 미치는 영향을 분석하였다. A suction caisson has been widely used for anchor and foundation of offshore structures due to its broad application, simple installation, and rapid construction. In design of suction caisson foundation, the bearing capacity and the stability of soil are mainly dealt with and analysis methods for them are presented in design codes related to the foundation. On the other hand, the method for structural safety analysis of the suction caisson is not generalized, in particular for load modeling of the caisson under suction. Consequently, there are difficulties in design of the caisson cross section. For this reason, this study analyzed the magnitude and distribution of pore water pressure on inner and outer surface of the caisson using theoretical and numerical seepage analyse, and an approach to reasonably estimate the load applied to the structural analysis of the caisson was presented. Furthermore, effects of penetration depth, anisotropy of permeability, and suction pressure on the pore water pressure were analyzed.

지반스프링 모델을 활용한 점성토 지반에서 석션앵커의 파주력 고찰

권오순,박해용,강현,오명학 (사)한국연안방재학회 2023 한국연안방재학회지 Vol.10 No.2

In this paper, a soil-spring model was applied to evaluate the holding capacity according to the loading position of the suction anchor. The API(2010) method, which is mainly applied to small-diameter piles, the PISA(2015) method, which recently introduced research results in offshore wind power design, and the Jeanjean(2009) method, which was presented as a model suitable for large-diameter piles in cohesive soil, were analyzed. A comparative review of the finite element analysis(ALE) was applied was performed for the conditions. A procedure for calculating the holding capacities for each loading position of the suction anchor was established using the soil-spring model, and it was confirmed that it was a method that could be used practically. When the soil-spring model of Jeanjean(2009) was applied, the results (5~10%) most similar to the FEM(ALE) analysis results in tendency and holding capacity could be obtained.

60m급 파력발전 실해역 시험장 선정을 위한 제주도 차귀도 해역의 해저 지층 탐사

김한수(Hansoo Kim),김정록(Jeongrok Kim),조일형(Il-Hyoung Cho),팽동국(Dong-Guk Paeng),최종수(Jong-Su Choi) 한국해양공학회 2017 韓國海洋工學會誌 Vol.31 No.4

The purpose of this study was to investigate the sea floor using a seismic profiler in the northern part of Chagwi-do of Jeju Island in order to select the optimal location for the 60-m-class berth of a sea test bed for wave energy converters and provide basic environmental data for designing a suction anchor. The echo types of the seismic profiles were classified based on the study of Kim et al. (2016a), and the location for installing the suction anchor was selected based on a sediment thickness of more than 10 m. The physical properties of the surface sediments were determined by analyzing the sediment samples obtained from 16 grab sample points. Based on the investigation and analysis, we proposed a survey area in the North-Eastern sea as an optimum location for the 60-m-class berth where the suction anchor could be installed.