海上风电嵌岩群桩基础竖向承载特性模型试验研究

MODEL EXPERIMENTAL STUDY ON AXIAL BEARING PROPERTIES OFROCK-SOCKETED PILE GROUP FOR OFFSHORE WIND TURBINE

以福建海域风电场中使用钢管-混凝土组合桩的嵌岩群桩高承台基础为研究对象,通过室内缩尺模型试验的方法,对嵌岩群桩基础的竖向抗压承载特性和破坏机理进行研究,并与嵌岩单桩基础进行对比。研究结果表明:加载前期,钢管-混凝土组合桩群桩之间的覆盖层和基岩与桩作为一个整体共同承载来自上部的下压荷载,这导致了群桩的桩端轴力增加幅度相对单桩较小,以及群桩的桩端阻力发挥受限,向下的应力较单桩更难扩散;加载后期,群桩之间出现连接裂缝,削弱了桩间土的承载能力,使得群桩的桩端阻力和端阻比增加明显。此外,为避免群桩效应的影响,钢管-混凝土组合桩的桩间距应在3倍桩直径以上。

Taking the high cap foundation of rock-socketed pile group using concrete filled steel tubular composite pile in Fujian offshore wind farm as the research object,the vertical compressive bearing characteristics and failure mechanism of rock-socketed pile group were studied by scale model test,and compared with rock-socketed single pile.The results show that in the early stage of loading,the overburden and bedrock between the concrete filled steel tubular composite pile group and the pile as a whole bear the upper compressive load together,which leads to the smaller increase of the axial force at the pile end of the pile group than that of the single pile,and the resistance at the pile end is limited,the downward stress is more difficult to diffuse than that of the single pile.In the later stage of loading,the connection cracks appear between the piles,which weakens the bearing capacity of the soil between the piles,and makes the pile end resistance and end resistance ratio of the pile group increase obviously.In addition,in order to avoid the influence of pile group effect,the pile spacing of concrete filled steel tubular composite piles should be above 3 times the pile diameter.