近海风机伞式吸力锚基础（USAF）结构设计动力响应与灾变控制

发布时间：2018-03-11 04:31

  本文选题：近海风机　切入点：伞式吸力锚基础（USAF）　出处：《中国海洋大学》2014年硕士论文　论文类型：学位论文

【摘要】：近海风力发电是未来国家风电能源战略的核心，风机基础作为海洋构筑物，长期面临复杂海况和海底地质活动的考验，其在风、浪、流等荷载联合作用下的稳定性分析成为风电设计面临的巨大挑战。现役的海上风机基础大都存在波浪对基础周边海床冲蚀严重，水平承载力在循环荷载下衰减快，安装施工对海底环境扰动大等弊端，适于近海风电场建设的新型风机基础型式迫切需要提出，风机基础结构选型和设计成为影响大容量（MW级）、大规模风电开发研究的热点问题。本论文基于已有风机基础存在的弊端，设计提出了一种新型伞式吸力锚基础（USAF），并通过理论分析、模型试验、数值模拟等手段较系统的研究了USAF基础的承载特性和动力响应问题，运用海床土临界液化孔压比准则，构建了USAF基础的灾变控制监测预警体系。具体研究工作如下： 1、以黄三角典型近海沉积环境与水动力特征为例，指出近海风机基础结构选型和承载性能研究的重要性，进而提出了自主设计的伞式吸力锚基础，并对USAF基础的设计原理、结构优势、沉贯机理、安装方法等进行了详细的说明。 2、运用极限分析原理对USAF基础的水平承载特性展开分析，重点研究了各破坏区土体许可滑动状态和许可速度场，通过对土体破坏机制和破坏区许可速度场的建立，推导了内部能量耗散率和外力功功率表达式，继而提出了USAF基础的水平极限承载三维上限解法。通过算例将上限解与有限元模拟结果对比，证明了上限解法在求解USAF基础水平极限荷载中的合理性。 3、通过室内土箱试验分析了USAF基础在水平静力加载、水平循环加载和竖向拉拔荷载下的锚-土相互作用规律。模拟了USAF在水平低频荷载和一次风暴潮作用后锚体的变位响应，指出锚枝对动力荷载激励下的锚体变形具有抑制作用。发现并阐述了USAF在上拔过程中的“分段现象”，提出了一种确定USAF基础极限抗拔荷载的动力学搜索方法，并得到验证。 4、使用ANSYS软件分析了除风荷载之外的波浪荷载、地震荷载和冰荷载等海洋动力载荷对海上风机USAF基础动力承载特性的影响。重点分析了主筒、筒裙、锚枝的不同模态振型和振动规律，讨论了0～130Hz外荷载激励作用下USAF结构的谐响应状况，基于功率谱密度（PSD）法分析了波浪荷载作用下USAF结构的振动响应，研究了地震荷载和冰荷载两类随机荷载对USAF基础结构振动的影响。 5、依据Geo-Studio软件在岩土非线性分析中的优势，采用拟静力法对风浪荷载下USAF周围地基土变形及破坏模式进行了有限元模拟，，模拟发现土体内部最大剪应力发生在锚趾转动区和锚枝下压区，并结合土体内部剪应力应变分布对主筒和筒裙转动点的位置进行了分析。最后，将USAF基础与常规吸力锚基础进行同等水平荷载下的地基土变形比较，证明了新型USAF基础的结构承载优势。 6、从海床土微观结构入手，综合考虑渗流场和应力场的耦合作用，构建了海床土液化破坏的重正化群模型，阐述了饱和海床土宏观液化与微观强度的定量关系，提出了海床土临界液化孔压比概念，绘制了不同土质海床的临界液化判别准则表，并对其影响因素进行了分析，准则对USAF基础的灾变控制监测预警具有重要意义。 7、介绍了USAF基础智能监测方法和预警系统的实现过程，通过孔压传感器与锚体的组合设计，使得海床土临界液化孔压比准则在判别风机基础稳定性中得以应用。监测过程中主筒侧壁和弹性盒内布设的孔压传感器分别采集锚体周围分层地基土的实时孔压数据，在数据处理上，引入模糊判别因子对监测孔压值进行分析，一旦孔压值超过临界液化孔压，系统就会发出报警信号，论文最后对监测预警系统的工作原理和运作程序进行了说明。
[Abstract]:Offshore wind power is the core of the future national energy strategy of wind power, wind turbine foundation as the marine structures, facing complex sea conditions and seabed geological activity test, in the wind, wave, flow and stability analysis under the combined action of load has become a huge challenge facing the wind power design. The most active offshore wind turbine foundation there are waves on the basis of the surrounding seabed erosion is serious, fast decay under cyclic loading capacity, the installation of construction defects undersea environment disturbance, a new fan base type is suitable for the construction of offshore wind farms is an urgent need to put forward, the selection and design of wind turbine foundation become large capacity (MW), a hot issue in the research of mass the development of wind power. The drawbacks of existing wind turbine based on the design, proposed a new umbrella type suction foundation (USAF), and through theoretical analysis, model test, numerical simulation A systematic study of the bearing characteristics and dynamic response of USAF foundation is carried out. Based on the criterion of pore water pressure ratio of seabed soil, a monitoring and early warning system for USAF based disaster control is constructed.
1, in the Yellow River Delta typical coastal sedimentary environment and hydrodynamic characteristics as an example, points out the importance of offshore wind turbine foundation structure selection and bearing performance research, and then puts forward the umbrella type suction foundation is designed, and the design principle of USAF based structure, penetration mechanism and installation method in detail description.
2, analyze the application level of USAF based on the principle of limit analysis of bearing characteristics, focusing on the soil damage area license and license sliding state velocity field, through the establishment of soil failure mechanism and failure zone permit velocity field, the internal energy dissipation rate and external power are deduced, and then puts forward the three-dimensional bearing upper limit solution the level limit of USAF foundation. By contrast with the upper bound solution of finite element simulation results, proved the rationality of upper limit solution based on USAF level for limit load.
3, through indoor soil box experiments of USAF based on horizontal static loading, cyclic loading and the law of horizontal vertical pullout loads of anchor soil interaction. The simulation of USAF in low load and a storm surge after the anchor body displacement response, pointed out that the anchor branch on the dynamic load under the excitation of the anchor body the deformation has inhibitory effect. And the USAF in the pulling out process of "block phenomenon", proposed a USAF based dynamic determination of ultimate pullout load search method, and verified.
4, the use of ANSYS software to analyze the wave load in the wind load the seismic load and ice load and dynamic load bearing characteristics of marine influence on offshore wind turbine based on USAF power. Focus on the analysis of the main cylinder, Tongqun, different vibration modes and vibration law of anchor branches, discussed the status of response of USAF structure harmonic function 0 to 130Hz under external loads, based on power spectral density (PSD) method to analyze the vibration response of USAF structures under wave loading, studied the effect of seismic load and ice load of two stochastic load on USAF based structural vibration.
5, based on the advantage of Geo-Studio software in the nonlinear analysis of rock and soil, using the pseudo static method of foundation soil under wind and wave loads around USAF deformation and failure model of finite element simulation, simulation of soil maximum shear stress occurs in the anchor and anchor toe rotation area under branch pressure area, and combined with the soil shear stress the strain distribution of the main cylinder and the skirt of the rotation point position were analyzed. Finally, the USAF based and conventional suction anchor compare equal deformation of soil under horizontal load, proved that the structure of the new USAF foundation bearing advantages.
6, starting from the seabed soil microstructure, considering the coupling of seepage field and stress field, construction damage liquefaction of seabed soil renormalization model, describes the quantitative relationship between macro and micro liquefaction strength of saturated soil, the soil critical liquefaction pore pressure ratio concept, drawing on different soil the seabed critical liquefaction criterion, and analyzes its influencing factors, has an important significance criterion for USAF based disaster control monitoring and early warning.
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