- 學位論文
離岸風力發電機單樁式基礎塔架之混凝土接點改良分析
Structural analysis for grouted joint of offshore monopile foundation
摘要
離岸風力發電機塔架分為數種，主要依據水深以及海床土壤狀況而定，而目前世界上最廣泛使用的形式為單樁式基礎的塔架。單樁式塔架利用混凝土接點的方式將基樁以及上方支撐整架風機的套管接合在一起，其有助於基樁打入海床時所造成的偏心問題，但這使得混凝土接點變成相對容易造成破壞的位置。本文研究的重點即在於混凝土接點的破壞行為，並嘗試提出幾何結構上的改良方式，利用數值模擬以及實驗驗證分析其結果，得出最佳的改良方式為何。 本文數值模擬使用Abaqus有限元素分析軟體建構2MW風機塔架2D以及3D靜態分析模型，分析混凝土接點整體之破壞位置及極值比較，另外分析改良形式的3D有限元素模型，討論修改後模型相對於原始模型應力的改善程度。 實驗部分利用拉伸試驗機對縮小尺寸之3.6MW離岸風機塔架實行3點彎矩實驗，試體分成原始形式以及改良形式，量測其負載-位移圖並討論其改善程度。最後就數值模擬以及實驗結果相互比較以得出改良形式是否可行並且有限元素分析為具參考性的。 根據計算之結果，本文中提出之改良形式不管在局部或者整體上的應力皆有所改善，以應力極值而言，2MW風機塔架在易破壞的兩種位置以最佳改良的形式分別可以改善7%以及13%，整體混凝土的應力分布在拉力側亦有減緩；而縮小尺度的實驗以及數值模擬中極限負載則可提升20%，勁度則是提升15%以上。
並列摘要
There are several types of offshore wind turbine towers. The choice of the tower depends on the water depth and the soil situation of sea bed. Presently, the monopile foundation is one of the most common types. It usually consists of a ‘grout joint’ to connect the pile and the sleeve and supports the wind turbine. The grout corrects the alignment of the sleeve and the pile from imperfection when hammering it to the sea bed. Nevertheless, the destruction of the concrete remains critical. This article focuses on the damage behavior of the grout joint, and proposes a few types of improved joints for the connection of the monopile. Numerical analysis and experiments are performed for the general type and the improved types of the joints. In the numerical analysis, we use Abaqus/CAE software package to construct the 2D and 3D models of 2MW offshore wind turbine. The damage location and maximum stress from the static analysis are discussed. We also build the numerical models of the tower with improved types of the joint, and discuss the stress reduction. In the experiments, we use the MTS machine to perform the three-point bending tests for the small scale 3.6MW monopile foundation. We focuses on the general type and one of the improved types of the joints. We measure the force-displacement data and discuss the improvement. Finally, we compare the results between simulations and the experiments. According to the results of simulations and experiments, the proposed improved type of grout joint demonstrates apparent improvement. In 2MW wind turbine, the average maximum stress reduction is 7% and 13% from the two locations. In the small scale experiment, the maximum load can be increased by 20% and the stiffness can be increased by 15%.