Effect of Sloping Seabed on the Stability of Jack-up Installation Vessel during Construction

• Main Authors: Lin,Shang-Zhi, 林上智
• Other Authors: Fan,Chia-Cheng
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/gqz9g7

碩士 === 國立高雄第一科技大學 === 營建工程系碩士班 === 106 === Due to global warming and Fukushima nuclear disaster, offshore wind power has become a promotional project in Taiwan. However, building the offshore wind farm needs to rely on the self-elevating platform vessel for lifting of the machine components, but there is no independent jack-up installation vessel in Taiwan. Therefore, it is necessary to rely on foreign lease. If the support foot of hull penetrates into the uneven seabed topography in the construction phase, causing the foot to the support base exceed the allowable range of the stress behavior of the footing, damage will be caused to the hull and delay the construction period and the property loss. Meanwhile, investigating the effect of sloping seabed on the stability of jack-up installation vessel during construction is vital. In this study, Plaxis 3D was used to analyze the effect of slop seabed on the stability of jack-up installation vessel during construction, Besides, Plaxis 3D was also utilized to explore the influence of slop seabed on the support foot and hull of jack-up platform vessel, the soil parameter used Changbin outer sea soil data to set up and simulated in sandy soil. The hull structural parameters were set as the model structure with reference the self-elevating platform ship carrier number (Torben), and three kinds of soil conditions were established, the slope conditions were 0,5,and10-degree, respectively. The support foot penetration operation was simulated by displacement control. With the analysis of the platform vessel to penetrate the slope seabed under full load, the hull displacement of the platform vessel, the stress distribution of the support foot, the penetration behavior of the seabed soil. The vessel safety analysis of the three kind of hoist operations and the bearing capacity of the single support foot penetrated into the slop seabed. Research results: When single support foot penetrated into the slop seabed, the bearing capacity of the supporting foot was affected by the angle of the slope seabed, causing inclined loading, which reduced the bearing capacity of the foot got down. (2) After the support foot penetrated into the soil, it generated large shear force and moment at the connect of the vessel and supporting foot. If the shearing force and moment were too large than the original design range, it will result in a problem that the footing process was not smooth or the support foot was deformed, causing problems with the safety of the vessel. (3) When the angle of the slop seabed increases, the stress and displacement of the hull and soil increases with the angle of the slope seabed. Therefore, when the platform vessel is engaged in the operation, if the vessel's steel strength is insufficient or the penetration of the soil is a weaker soil layer or the angle of the inclined seabed is larger (>10 degrees), the construction safety of the hull will be challenged.