预应力锚栓式风力发电塔基础的灌浆层经常出现开裂掉角现象,断面整齐光滑。采用FRANC-2D建立灌浆层部位的线弹性断裂力学模型,分析裂缝发展路径及断裂强度因子的变化情况。模拟结果显示：裂缝由灌浆层和钢板的交界处产生,开始沿着水平方向向外缘发展,随后沿着45°向下开展直至开裂至灌浆层边缘;I型断裂强度因子在裂缝开展过程中先减小后增大再减小,且在裂缝开展至0.2倍总长附近达到局部最小值,此点可用于评估灌浆层的断裂承载力。不同灌浆层厚度和外伸宽度的参数化分析结果显示：厚度增大后,裂缝较易开展;宽度增大后,裂缝较难开展,且宽度影响更大。基于参数化分析及量纲分析,提出灌浆层断裂承载力的计算公式和可供工程参考的设计建议,并结合工程算例的线弹性断裂力学和疲劳断裂分析,验证了公式的有效性和适用性。
Abstract
The grouting layer of the wind turbine foundation of with prestressed anchor bolts often occurred cracking and fracturing near its edge. The fracture section is neat and smooth. The linear elastic fracture mechanics model of the grouting layer is developed by FRANC-2D to analyze the crack path and the history of the stress intensity factors. The simulation results show that the crack begins at the junction of the grouting layer and the steel plate, and then propagates almost horizontally to the outer edge. Subsequently, the crack develops downward along 45 degrees until reaches the edge of the grouting layer. The mode-I stress intensity factor decreases at first, then increases, and decreases again during crack propagation. A local minimum value occurs near 0.2 times the total length of the crack, which can be used to evaluate the ultimate bearing capacity of the grouting layer. The parametric analyses of different grouting layer thicknesses and extension widths show that crack propagation is easier with the increasing thickness, while more difficult with the increasing extension width. Moreover, the influence of the extension width is more obvious. Based on parametric analyses and dimensional analyses, the calculation formula for the ultimate bearing capacity of the grouting layer and the design suggestions for engineering practices are proposed. The validity and applicability of the formula are verified by the linear elastic fracture mechanics and fatigue fracture analyses of practical engineering.
关键词
断裂力学 /
裂纹扩展 /
断裂强度因子 /
风力发电塔 /
基础开裂
Key words
fracture mechanics /
crack propagation /
stress intensity factors /
wind turbine tower /
cracking of the foundation
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] JENQ Y, SHAH S P.Two parameter fracture model for concrete[J]. Journal of engineering mechanics, 1985, 111(10): 1227-1241.
[2] BAŽANT Z P, OH B H. Crack band theory for fracture of concrete[J]. Matériaux et construction, 1983, 16(3): 155-177.
[3] HILLERBORG A, MODÉER M, PETERSSON P E. Analysis of crack formation and crack growth in concrete by means of fracture mechanics and finite elements[J]. Cement and concrete research, 1976, 6(6): 773-781.
[4] 徐世烺, 赵艳华. 混凝土裂缝扩展的断裂过程准则与解析[J]. 工程力学, 2008, 25(增刊2): 20-33.
XU S L, ZHAO Y H.Analysis and criterion of fracture process for crack propagation in concrete[J]. Engineering mechanics, 2008, 25(S2): 20-33.
[5] MAZARS J.A description of micro- and macroscale damage of concrete structures[J]. Engineering fracture mechanics, 1986, 25(5/6): 729-737.
[6] 李庆斌, 张楚汉, 王光纶. 混凝土Ⅰ型裂缝动静力损伤断裂分析[J]. 土木工程学报, 1993, 26(6): 20-27.
LI Q B, ZHANG C H, WANG G L.Static and dynamic damage fracture analysis of mode Ⅰ crack in concrete[J]. China civil engineering journal, 1993, 26(6): 20-27.
[7] 蒋梅玲, 金贤玉, 田野, 等. 基于断裂力学和损伤理论的混凝土开裂模型[J]. 浙江大学学报(工学版), 2011, 45(5): 948-953.
JIANG M L, JIN X Y, TIAN Y, et al.New concrete cracking model established based on fracture mechanics and damage theory[J]. Journal of Zhejiang University (engineering science), 2011, 45(5): 948-953.
[8] PARIS P, ERDOGAN F.A critical analysis of crack propagation laws[J]. Journal of basic engineering, 1963, 85(4): 528-533.
[9] RITCHIE R O.Mechanisms of fatigue-crack propagation in ductile and brittle solids[J]. International journal of fracture, 1999, 100(1): 55-83.
[10] BAZANT Z P, SCHELL W F.Fatigue fracture of high-strength concrete and size effect[J]. ACI materials journal. 1993, 90(5): 472-478.
[11] LE J L, MANNING J, LABUZ J F.Scaling of fatigue crack growth in rock[J]. International journal of rock mechanics and mining sciences, 2014, 72: 71-79.
[12] ERDOGAN F, SIH G C.On the crack extension in plates under plane loading and transverse shear[J]. Journal of basic engineering, 1963, 85(4): 519-525.
[13] HUSSAIN M A, PU S L, UNDERWOOD J H.Strain energy release rate for a crack under combined mode I and mode II[C]// Proceedings of the 1973 National Symposium on Fracture Mechanics. Baltimore, MD, USA, 1974.
[14] SIH G C.Strain-energy-density factor applied to mixed mode crack problems[J]. International journal of fracture, 1974, 10(3): 305-321.
[15] VOGEL A, BALLARINI R.Ultimate load capacities of plane and axisymmetric headed anchors[J]. Journal of engineering mechanics, 1999, 125(11): 1276-1279.
[16] ATAHAN H N, TASDEMIR M A, TASDEMIR C, et al.Mode I and mixed mode fracture studies in brittle materials using the Brazilian disc specimen[J]. Materials and structures, 2005, 38(3): 305-312.
PDF(2522 KB)
