黏土地基海上风机三桩基础循环响应分析

在恶劣的海洋环境中，海上风机三桩基础长期承受随机风荷载和波浪荷载，这些荷载会导致基础产生较大的倾覆力矩，进而产生过大的转角和沉降变形，导致风机的整体失稳破坏。因此，探究海上风机三桩基础在循环荷载作用下的承载特性具有重要意义。本文采用弹塑性单边界面本构模型描述黏土的动应力-应变响应，建立了经典5 MW 海上风机三桩基础系统的三维有限元模型，开展了黏土地基三桩基础在单调、循环荷载作用下的三维数值模拟分析。研究结果表明：加载方向对三桩基础的极限承载力有显著影响，三桩基础的承载力由受压桩的抗压承载能力决定；在单向循环荷载作用下，背风桩和迎风桩之间的累积沉降差导致三桩基础发生旋转；在双向循环荷载作用下，当荷载幅值较小时，三桩基础的转角随循环次数逐渐增大，而当荷载幅值较大时，三桩基础会表现出“自我修复”特性。

英文摘要:

In the harsh marine environment, Offshore Wind Turbine (OWT) tripod pile foundations are subjected to long-term lateral cyclic loads from wind and waves, these loads will lead to a large overturning moment of foundations, produce excessive rotation angle and settlement, and cause destabilization of the OWT. Therefore, it is significance to investigate the bearing characteristics of OWTs tripod pile foundation under cyclic loading. A three-dimensional finite element model of the classic 5 MW OWT tripod pile foundation system was established by using an elastic-plastic bounding surface constitutive model to describe the dynamic stress-strain response of clay. The three-dimensional numerical simulation analysis of tripod pile foundation in clay under monotonic and cyclic loads was carried out. The research results indicated that the loading direction has a significant impact on the ultimate bearing capacity of tripod pile foundation, and the bearing capacity is controlled by the compressive bearing capacity of the compressed piles. Under one -way cyclic loading, the cumulative settlement difference between Windward pile and Leeward pile causes rotation of tripod pile foundation. Under two-way cyclic loading, the rotation angle of tripod pile foundation gradually increases as the cycle number increases when the load amplitude is small, while the tripod pile foundation exhibits a feature of “self-healing”when the load amplitude is great.

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