自升式平台桩靴基础的全工作周期稳定性分析

近海石油、天然气和风电对保障我国能源供给和能源结构升级起着举足轻重的作用。渤海是我国近海能源最丰富的地区之一，也是山东省新旧动能转换中能源基础建设的关键区域。自升式平台被广泛用于近海能源的开发，如钻井、修井、风机打桩与叶片吊装，但自升式平台在预压、作业和拔桩过程中频繁遭遇各种事故，其中大多与桩靴基础相关。本项目针对粉土的特殊性质、渤海复杂的地层和冲刷条件，发展离心机模型试验、大变形有限元方法和理论分析等技术手段，深入研究实际应用中最常遇到的桩靴预压穿刺、承载力不足与拔桩困难。突破以往孤立考虑桩靴特定阶段行为的研究范式，再现“预压-作业-上拔”全工作周期的桩靴大幅值位移及粉土中的部分排水条件，构建简化但合理的多层土破坏模型，提出能够用于工程设计的桩靴穿刺、复合承载力包络面和抗拔力预测方法，实现考虑前期效应的桩靴实时行为预测。研究成果将为渤海中自升式平台的安全、高效运营提供科学依据和技术支撑。

Offshore energy resources, including oil, gas and wind power, play a vital role in China’s energy supply and optimization of primary energy structure. Bohai Sea is one of the richest areas in offshore energy resources in China. It is also the key area for energy infrastructure construction as part of the “new and old kinetic energy conversion of Shandong Province”. Jack-up rigs are widely used in the offshore energy projects for activities such as drilling, well maintenance and installation of piles and blades for offshore wind turbines. However, accidents related to spudcan foundations are prevalent during the processes of preloading, operation and extraction. In this proposed project, thorough research will be carried out with particular interest in the unique properties of silt sediment and the complex soil and scouring conditions in Bohai Sea. Centrifuge modeling, large deformation finite element modeling and analytical modeling techniques will be developed to study the commonly encountered geotechnical hazards of spudcan, including punch-through, insufficient bearing capacity under combined loading, and difficulties in spudcan extraction. Unlike previous studies which only considered a certain stage of the spudcan installation-operation-removal process, the entire process will be modeled in this project with the large amplitude of spudcan movement and partly drainage condition of silt considered. The key aim is to establish a simplified but effective analytical model, based on which a design framework will be developed for assessing spudcan resistances or bearing capacities in stratified soils during punch-through, combined loading and extraction. The proposed framework will be able to predict real-time spudcan behaviors incorporating the effect of preceding scenarios. The outcomes of the proposed research will provide scientific basis and technical support for the safe and efficient deployment of jack-up rigs in Bohai Sea.