波浪作用下海上风电复合筒型基础周围海床动力响应研究

发布时间：2018-11-27 19:12

【摘要】：波浪是影响近海结构物稳定性的重要因素,在循环波浪作用下,海床内部孔隙水压力会随之产生循环交替变化,超孔隙水压力的增长引起海床内部应力分布变化,使其抗剪强度减弱,对海床及上部结构物稳定性产生威胁。本文通过耦合开源流体力学软件OpenFOAM和大型通用有限元分析软件ABAQUS建立集成模型,对复合式筒型风电基础周围海床在波浪作用下动力响应进行研究。论文主要内容及结论如下:(1)建立三维海床响应数值模型,与立波、行进波作用下海床响应实验值和解析解进行比较,验证模型的合理性。(2)建立开源流体力学软件Open FOAM和大型通用有限元分析软件ABAQUS集成模型,对波浪作用下海上风电复合筒型基础周围海床响应进行模拟。结果表明,复合筒型基础背浪侧边缘处海床孔压沿深度方向衰减速度较快,迎浪侧孔压衰减速度较慢;筒型基础筒内部从筒裙下部渗流传入的孔压较小,不易发生液化。(3)分析海床土体参数对筒型基础周围海床动力响应的影响。认为海床的各向异性越明显,孔隙水压的衰减速度越慢;海床透水性及剪切模量随深度呈指数分布变化对孔压衰减速度无明显影响,线性分布则会使孔压衰减速度变慢。(4)建立负压沉入式筒型风电基础周围海床响应模型,对负压沉入对海床孔隙水压响应的影响进行了模拟分析。结果表明,施加的负压值大小对复合式筒型基础边缘处孔压分布影响较大,沉放下沉速度对海床中孔隙水压分布不会造成明显影响,未完全沉入筒型基础会使其附近海床负压减小,经负压沉入过程的海床液化范围相比未经沉入过程海床有所减小。(5)对实际工程条件下的海床响应和液化进行模拟分析,土体分层对波浪作用下海床响应有一定的影响,两种情况下复合式筒型基础周围海床均未发生液化。
[Abstract]:Wave is an important factor affecting the stability of offshore structures. Under the action of cyclic wave, the internal pore water pressure of the seabed will change alternately, and the increase of the excess pore water pressure will lead to the change of the stress distribution in the seabed. The shear strength is weakened and the stability of seabed and superstructure is threatened. In this paper, an integrated model is established by coupling the open-source hydrodynamic software OpenFOAM with the large-scale general finite element analysis software ABAQUS, and the dynamic response of the seabed around the composite cylindrical wind power foundation under wave action is studied. The main contents and conclusions of the paper are as follows: (1) A three-dimensional seabed response numerical model is established, which is compared with the experimental results and analytical solutions of the seabed response under the action of vertical wave and traveling wave. (2) the integrated model of open-source fluid dynamics software Open FOAM and large-scale general finite element analysis software ABAQUS is established to simulate the response of offshore wind power composite cylinder foundation around the sea bed under wave action. The results show that the pore pressure of the seabed at the edge of the back wave side of the composite cylindrical foundation attenuates faster along the depth direction, and the pore pressure at the wave side decreases more slowly. The pore pressure from the bottom of the cylinder skirt is small and the liquefaction is not easy. (3) the influence of the soil parameters of the seabed on the dynamic response of the seabed around the cylindrical foundation is analyzed. It is considered that the more obvious the anisotropy of the seabed is, the slower the attenuation rate of pore water pressure is. The variation of permeability and shear modulus with depth has no obvious influence on the attenuation velocity of pore pressure, but the linear distribution will slow down the attenuation rate of pore pressure. (4) the response model of seabed around the negative pressure immersed cylindrical wind power foundation is established. The influence of negative pressure sinking on the pore pressure response of seabed is simulated and analyzed. The results show that the value of negative pressure exerts a great influence on the pore pressure distribution at the edge of the composite cylindrical foundation, and the settling velocity has no obvious effect on the pore water pressure distribution in the seabed. If the submersible cylindrical foundation is not fully submerged, the negative pressure of the nearby seabed will be reduced, and the liquefaction range of the seabed during the process of sinking under negative pressure will be reduced compared with that of the seabed without sinking. (5) the response and liquefaction of the seabed under the actual engineering conditions are simulated and analyzed. Soil stratification has a certain effect on the response of the seabed under the wave action, and there is no liquefaction of the seabed around the composite cylindrical foundation in both cases.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV139.2

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