波浪作用下海上风电场桩基土体液化响应研究—以黄河三角洲为例

This project focuses on the core problem of complex loads-pile foundation-seabed soil body interactions in the development of offshore wind power. This project aims to clarify the physical and mechanical mechanism among the interactions and establish feasible quantitative evaluation method accodingly, in which laboratory tests, insitu measurements, theoretical analysis and numerical simulation may be carried out based on the frame work of marine soil mechanics. The main contents of this research include: The development process and estimation of liquefaction in the seabed around the pile foundation of offshore wind turbines under the combination of loads such as wave, current, and wind in both normal and extreme sea conditions; The liquefaction corrosion and liquid transportation of seabed soil due to coupling effects of pile, seabed soil and waves; The lateral deformation and bearing capacity of the pile foundation of wind turbines that affected by the complete of partial liquified seabed soil. The background of this research is selected in the modern subaqueous Yellow River Delta, where abundant offshore wind resources exist, and with complex marine engineering environments and complex geological engineering conditions. The project is intended to explore the dynamic transitions of the properties of seabed soil around the pile foundation of offshore wind turbine and estimate the possible environmental behaviour of this process, and try to build up the mathematical model to calculate the lateral deformation and evaluate the stability of offshore wind turbine considering both the direct loads on the structure and the liquefaction effects of seabed soil. The results of this project will inprove the understanding of waves—structure—seabed interactions, and provide a technical support for the design, construction and stability evaluation of pile foundation of offshore wind turbine in the Yellow River Delta.

本课题针对海上风电开发过程中复杂荷载-风电场桩基-海床土体相互作用这一科学问题，从海洋土力学角度出发，通过室内试验、野外调查、理论分析以及数值模拟等研究方法，力图理清三者相互作用的物理力学机制，建立相应的定量计算评价方法。主要研究内容包括：常规和极端海况条件下，波浪、潮流和风荷载联合作用下桩基土体液化及发展过程、液化深度确定；基于桩基-海床土-波浪耦合作用的桩基周围海床土体液化侵蚀与流体运移过程；桩周土体液化对风电桩基水平变形和稳定性的影响。课题以海上风电资源丰富、但具有复杂海洋工程环境和复杂工程地质条件的黄河水下三角洲作为研究区域，探究复杂荷载下海上风电场桩基周围海床土性态变化及其环境行为，建立复杂荷载直接作用及桩周土体液化情况下海上风电场桩基变形和稳定性评价方法。研究成果将增进对波浪-结构-海床相互作用的认识，并为黄河三角洲海上风电场桩基设计，施工及运营过程中的稳定性评价提供技术支持。

近年来，随着国家建设“海洋强国”战略和“能源转型”政策的实施，海上风电得到了迅猛发展。本课题以海上风电资源丰富，但具有复杂海洋工程环境和复杂工程地质条件的黄河水下三角洲作为研究区域，针对海上风电开发过程中复杂荷载-风机基础-海床土体相互作用这一科学问题，采用室内试验、理论分析和数值计算的方法，开展了波浪作用下海上风电基础周围海床弹塑性动力响应、波致液化粉土中海上风电基础承载性能、局部冲刷对海上风机支撑系统水平承载性能三方面的研究。得到了黄河三角洲快速沉积环境中的海上风电基础周围海床瞬态孔隙水压力和残余孔隙水压力变化规律，推导出了累积孔隙水压力响应的简化分析方法，揭示了桩基-海床-波浪耦合作用的桩基土体液化过程和机理，明确了桩基土体液化深度和范围对桩基稳定性的影响规律，建立了波流导致桩基周围局部冲刷对海上风机支撑系统水平承载性能的影响机制。在此基础上，设计了能更好地保护周围土体、承载性能优势明显的伞式吸力锚基础（USAF），并得到了波致海床液化对伞式吸力锚基础承载性能的影响规律。研究成果将增进对波浪-结构-海床相互作用的认识，并为黄河三角洲海上风电场基础设计、施工及运营过程中的稳定性评价提供技术支持。