冲刷条件下砂土中单桩水平循环加载模型试验

Lateral Cyclic Loading Model Test of Monopile in Sand Soil under Scour Condition

近海风机大直径单桩在波浪的作用下承受水平循环荷载,并产生冲刷效应。采用一套可施加大周数循环荷载的试验装置,探究砂土中冲刷深度与加载路径耦合作用下大直径单桩累积变形特性与位移预测模型。通过对试验结果归一化和回归分析,得到位移预测模型,其为循环次数的幂指数和初次循环累计位移两者的乘积。研究发现,幂指数受加载路径和冲刷深度的影响较小;初次循环累积位移由两个相互独立的参数决定,即荷载峰值和控制循环幅值的荷载类型。荷载峰值受冲刷深度影响,荷载类型与冲刷深度无耦合关系。试验得到的位移预测模型的幂指数和初次循环累积位移公式可用于单桩长期水平循环累积位移的预测。

Monopiles of offshore wind turbines are subjected to horizontal cyclic loads under the action of waves,and scouring effects are produced.A test device that can apply cyclic loads of large number was used to explore the cumulative deformation characteristics and displacement prediction model of monopiles under the coupling effect of scouring depth and loading path in sand.By normalization and regression analysis of the test results,a displacement prediction model was obtained,which was the product of the power index of the cycles number and the cumulative displacement of the first cycle.It is found that the power index is less affected by the loading path and scouring depth.The cumulative displacement at the first cycle is determined by two independent parameters,namely the load peak and the load type that controls the cycle amplitude.The peak load is affected by the scouring depth.However,there is no coupling relationship between the load type and the scouring depth.The power index and the first cycle cumulative displacement formula of the displacement prediction model is obtained by the test,which can be used to predict the long-term horizontal cyclic cumulative displacement of monopiles.