海上风力发电复合筒型基础承载特性研究

发布时间：2018-05-08 06:28

本文选题：复合筒型基础 + 承载能力　；参考：《天津大学》2014年博士论文

【摘要】：宽浅式复合筒型基础作为一种新型海上风力发电基础,可以实现陆上建造、海上快速安装,其抗倾覆能力强、适用于各类地基土质,可以较好地解决开发近海风能资源所面临的问题。作为一种新型基础,经典的土力学地基承载力公式很难与其承载模式相匹配,其分仓结构使基础与土体较好的协同承载机制也与以往的相关基础研究有较大的不同,本文通过试验初步确定复合筒型基础的承载能力,在此基础上,采用有限元对其模拟计算并深入分析其单向、二维、三维的承载能力和失稳破坏机制,最后针对近海风电场的3MW复合筒型基础,分析其实际及理论极限承载力,并得出了其承载模式和传力机理。具体的研究内容及结果包括:分别在淤泥质粘土与砂土中进行复合筒型基础水平承载力试验,采用分级加载机制,符合试验预期,分别得出了筒型基础的土压力变化、位移变化;通过有限元对试验进行模拟分析并进行对比,分析表明,复合筒型基础的旋转中心随着荷载的增大从中轴线附近逐渐移动到沿加载方向的分仓板底部,最后位于距离筒顶约0.8倍的高度处;极限水平荷载下,根据试验、有限元及理论公式得出了淤泥质粘土中复合筒型基础主要区域的土压力分布,根据土压力分布规律计算出复合筒型基础的极限承载力,并对计算公式进行了修正;采用有限元分别对竖向及弯矩荷载进行模拟计算,竖向荷载作用下可以将筒型基础与筒内土体当做一个整体,得出了相应的失稳破坏模式,采用经验公式和理论公式对竖向极限承载力进行了计算并根据有限元结果修正了理论公式;弯矩荷载作用下,复合筒型基础旋转中心随着荷载的增加在接近筒底的区域从中轴线左侧(加载反向)逐渐移动到加载正向的分仓板附近;适当的竖向荷载可以改变旋转中心的位置、提高水平向及弯矩的极限承载力,淤泥质粘土中最大提高约2倍,砂土中的提高幅度更大;根据3MW海上风力发电风机的荷载值,得出宽浅式复合筒型基础的直径一般要大于27m、高度宜为7~12m,并分析了土质参数及筒土接触等对筒型基础承载能力的影响,计算了3MW复合筒型基础在考虑地基变形允许值及极限值两种情况下的水平、弯矩及竖向极限承载力及相应的二维包络线、三维包络面,并将其进行对比分析,分别得出复合筒型基础承载能力的允许上限值和理论上限值,说明复合筒型基础在实际工程中是比较安全的,根据有限元分析,明确了海上风电复合筒型基础的承载模式为以顶盖承载为主、筒壁承载为辅的‘顶承式’,过渡段顶部巨大的弯矩荷载可以通过弧形过渡段及预应力筋转化为底部较小的拉压应力,明确了预应力钢筋混凝土结构的弧形过渡段传力机理。
[Abstract]:As a new offshore wind power generation foundation, the broad-shallow composite cylindrical foundation can be constructed on land and installed quickly at sea, and its capsizing ability is strong, which is suitable for all kinds of foundation soil. It can solve the problem of developing offshore wind energy resources. As a new type of foundation, the classical formula of bearing capacity of soil mechanics foundation is difficult to match with its bearing mode, and its silo structure makes the better synergistic bearing mechanism between foundation and soil. In this paper, the bearing capacity of composite cylindrical foundation is preliminarily determined by experiments. On the basis of this, finite element method is used to simulate and analyze the bearing capacity and failure mechanism of unidirectional, two-dimensional and three-dimensional structures. Finally, aiming at the 3MW composite cylinder foundation of offshore wind farm, the practical and theoretical ultimate bearing capacity is analyzed, and the bearing mode and force transfer mechanism are obtained. The concrete research contents and results are as follows: the horizontal bearing capacity tests of composite cylindrical foundation are carried out in silt clay and sand respectively, and the soil pressure variation of the cylindrical foundation is obtained by using the graded loading mechanism, which accords with the test expectation. Displacement change; the finite element method is used to simulate and compare the test. The analysis shows that the rotating center of the composite cylindrical foundation moves gradually from the central axis to the bottom of the silo plate along the loading direction with the increase of the load. Finally, the earth pressure distribution in the main area of the composite tubular foundation in silt clay is obtained under the ultimate horizontal load, according to the test, finite element method and theoretical formula, which is about 0.8 times from the top of the tube. According to the distribution of earth pressure, the ultimate bearing capacity of composite cylindrical foundation is calculated, and the calculation formula is modified, and the vertical and moment loads are simulated by finite element method. Under the action of vertical load, the cylinder foundation and the soil in the tube can be regarded as a whole, and the corresponding failure mode of instability can be obtained. The vertical ultimate bearing capacity is calculated by empirical formula and theoretical formula, and the theoretical formula is modified according to the finite element results. With the increase of load, the rotating center of composite cylindrical foundation moves gradually from the left side of the central axis (the reverse of loading) to the area near the bottom of the cylinder, and the proper vertical load can change the position of the rotating center. The ultimate bearing capacity of horizontal direction and bending moment is increased by about 2 times in silt clay and more in sand. According to the load value of 3MW offshore wind turbine fan, It is concluded that the diameter of the broad-shallow composite cylindrical foundation is more than 27m and the height should be 72m.The influence of soil parameters and soil-tube contact on the bearing capacity of the cylindrical foundation is analyzed. The horizontal, bending moment and vertical ultimate bearing capacity of 3MW composite cylindrical foundation are calculated under the condition of considering the allowable value and limit value of foundation deformation, and the corresponding two dimensional envelope line and three dimensional envelope surface are compared and analyzed. The allowable upper limit value and the theoretical upper limit value of the bearing capacity of the composite cylindrical foundation are obtained respectively, which shows that the composite cylinder foundation is safe in practical engineering, according to the finite element analysis, It is clear that the bearing mode of offshore wind power composite cylinder foundation is' top bearing type 'with the top cover as the main load and the cylinder wall as the auxiliary load. The great moment load at the top of the transition section can be transformed into a smaller tension and compression stress at the bottom through the arc transition section and the prestressed tendons. The force transfer mechanism of the arc transition section of the prestressed reinforced concrete structure is clarified.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU476.1;TM614

【相似文献】