考虑水流侵入的海上风机基础灌浆连接段疲劳性能试验研究

Fatigue Tests on Grouted Connection Segment Specimens in Offshore Wind Turbine Structures Considering Water Ingression

海上风机基础中的灌浆连接段会在浪溅区或者水下工作,水流的侵入可能会对灌浆连接段的疲劳性能产生影响。本文设计了灌浆连接段局部性能试件,其中四个试件在空气中进行疲劳加载;同时,设计了一套水循环装置,让两个试件在水流侵入的条件下进行疲劳加载。试验结果表明,空气中疲劳荷载幅较大的试件A-3的灌浆材料出现了较宽的裂纹和剥落现象,试件加载的残余变形不断累积。同时,相同荷载幅条件下的两对试件相比,空气中的2个试件经过200万次疲劳循环总变形都在-0.7 mm以内;而水中的2个试件仅加载至26.4万次及6.4万次时,试验机位移便达到-10 mm,试验终止。由此可见,水流侵入会严重劣化灌浆连接段的疲劳性能。原因在于,水流会侵入灌浆材料裂纹内部,在荷载加载时,侵入的水分挤压灌浆材料局部的缝隙,加速裂纹的形成与开展;而在荷载卸载时,水流带走被压碎的灌浆材料,使得裂纹不稳定扩展,灌浆材料块体剥落。

Grouted connections(GCs)in offshore wind turbine structures work in marine splash zones and even submerged environments.The water ingression may influence the fatigue property of the GCs.This paper designed GC segment specimens.Four specimens were tested under fatigue loading in the air.Meanwhile,a water recycling setup was designed and two specimens were tested under fatigue loading in water ingression conditions.The results of the air show that in specimen A-3 with higher loading ranges,wide racks and grou material exfoliation were found.The residual displacement accumulated gradually,which eventually caused the termination of the test when it reached 5 mm after 1.3 million cycles.Furthermore,compared with two pairs of specimens tested in air and water ingression conditions,the two specimens in the air only had a total displacement less than-0.7 mm after two million load cycles.Meanwhile,the two specimens in the water ingression condition only endured 0.264 million and 64 thousand load cycles before the displacement of the top clamp reached-10 mm.The severe deteriorating effect of water ingression on the fatigue behavior of GCs was apparent.The reason should be that water could enter into micro cracks of grout material.When the load increased,water exerted pressures in cracks,which might accelerate the crack opening and formation of cracks When the load dropped,water could bring out the cracked grout particles,which made the cracks propagate unstably and grout material blocks peeled off.