海上风机导管架基础灌浆连接段轴向受压疲劳性能试验

Experimental Study on Axial Compression Fatigue Performance of Grouted Connection of Offshore Wind Turbine

灌浆连接段是海上风机导管架基础中的关键结构之一。通过缩尺灌浆连接段试件的轴向疲劳试验研究其疲劳性能。根据静力试验得到灌浆连接段极限承载力并确定疲劳荷载幅值,进行五个试件的轴向加载疲劳试验。轴心疲劳试件在经历200万次轴向疲劳荷载循环后,没有发现明显的灌浆层裂缝及钢管鼓曲。对于偏心疲劳试件,0.4的偏心率产生的弯矩引起了内钢管对灌浆层的较为严重的挤压,内管顶部偏心侧灌浆层出现明显开裂现象。通过对试验结果的分析可以得知,轴心加载试件在0.35Pu为上限的轴心疲劳荷载下的疲劳性能稳定,仅内管顶端出现了局部损伤,在引入偏心疲劳荷载后,会产生灌浆层的断裂现象,并且裂缝出现位置均为灌浆连接段顶部到第一个剪力键之间。因此,当风机基础结构设计中灌浆连接段的计算偏心率较大时,应引起设计工程师的注意。

The grouted connection section is one of the key structures in the jacket foundation of offshore wind turbines.The fatigue performance of the grouted connection section under different load ranges is studied through the axial fatigue test.The ultimate bearing capacity of the grouted connection section is obtained in the static test.Thereafter fatigue load ranges of the fatigue test are determined.Five sets of fatigue tests are carried out in this research.After the specimen has undergone two million axial fatigue load cycles,no obvious cracks in the grouting layer or bulging of steel pipe were found.For eccentric fatigue loading specimen with an eccentricity ratio of 0.4,the bending moment induced by eccentric loading caused serious extrusion of inner steel tube to grout layer.Obvious cracks appeared in the grout layer on the eccentric side of the top of the inner tube.Through the analysis of the test results,it can be informed that the fatigue performance of the specimen under the axial fatigue load with the upper limit of 0.35 Pu is stable,and local damage only occurred on the top of the inner tube.Under the condition of eccentric fatigue loading,cracks occur between the top of the grouted connection section and the first shear key.Therefore,in the offshore wind turbine foundation structure design,attention of the engineer should be drawn when the calculated eccentricity of the grouted connection is large.