斜坡与荷载方向协同作用的超大直径风电桩基承载机理与设计计算方法研究

Bearing mechanism and design theory of super large diameter pile foundation with synergistic action of slope and loading direction is a new task faced by the Marine wind power resources development and utilization. Therefore,study on relevant problems has a very important theoretical and practical significance. This project uses a combination of field investigation, laboratory test, numerical simulation and theoretical analysis methods, focusing on study of gradient of slope, loading direction, pile diameter, slope pile position, effect of pile - soil interface rough characteristics and soil properties on large diameter pile foundation bearing mechanism, reveals considering the coupling effect of slope and the loading direction on large diameter wind pile foundation bearing mechanism. This paper studies pile-soil system displacement field and stress field distribution and the calculation method of energy dispersive boundary by using PFC3D establishes different numerical calculation model based on indoor test data. On this basis, introducing energy principle and catastrophe theory to study large diameter pile in slope pile - soil system displacement development model, energy dispersive boundary , the energy equation’s building and catastrophe stability types and standards and other key issues respectively , then a bearing capacity and deformation calculation method of super large diameter wind pile foundation in slope will be set up , and analyzes the reliability of the applicable conditions of the method and the reliability of verifying theoretical method, finally proposes a set of super large diameter wind pile foundation design theory based on the energy and deformation control and provides a reference for relevant engineering design.

斜坡和荷载方向协同作用的超大直径风电桩基承载机理与计算方法是海上风电资源开发利用面临的技术难题。因此，开展相关问题研究具有重要的理论与实际意义。本项目拟采用现场调查、室内试验、数值模拟与理论分析结合的方法，研究斜坡坡度、荷载方向、桩-土界面粗糙度特性、斜坡桩位、桩径及土层特性对超大直径桩基承载特性的影响，重点揭示斜坡和荷载方向协同作用的超大直径风电桩基承载机理。基于室内模型试验，建立不同PFC3D三维数值模型，深入探讨桩-土体系位移场与应力场分布规律与能量扩散边界计算方法。在此基础上，引入能量原理与突变理论，解决斜坡超大直径桩基桩土体系位移发展模式、能量扩散边界、能量方程建立、突变失稳类型与准则等关键问题，从而建立基于能量和变形控制的超大直径风电桩基承载力和变形计算新方法，并分析该计算方法适用条件与可靠性，完善斜坡和荷载方向协同作用的超大直径风电桩基设计计算理论，为工程设计提供参考。

随着风电产业的迅速崛起，研究超大直径风电桩基承载机理，探讨考虑斜坡与荷载方向协同合作用的超大直径风电桩基承载力设计理论，对保障海上风电工程设计更趋合理与施工安全，提高风电桩基的耐久性均具有重要的理论和工程实际意义。本项目采用理论分析和数值试验方法，结合室内试验结果重点进行了四方面的研究：（1）斜坡超大直径风电桩基承载机理研究；（2）斜坡超大直径风电桩基桩土相互作用规律研究；（3）斜坡超大直径风电桩基能量扩散边界计算方法及位移场确定研究 ；（4）斜坡超大直径风电桩基计算方法与设计理论。通过研究初步探明了竖向荷载作用下斜坡桩承载特性、横向荷载下无粘性土坡刚性桩承载特性、横向荷载作用下双层土斜坡单桩承载特性；基于能量原理，推导出斜坡地基横向受荷桩的内力与位移理论计算方法。提出了横向荷载下无粘性土坡坡尖和有临坡距的刚性桩非线性分析方法；建立了横向荷载下无粘性土坡刚性桩离散元分析模型、探明了桩－土相互作用规律；提出了一种斜坡竖向受荷桩沉降计算方法；利用基于能量原理考虑斜坡效应的桩基非线性理论分析方法，探讨分析完全不排水多层黏土地基中斜坡场地条件下的斜坡坡度、临坡距、土层厚度比以及不排水抗剪强度影响斜坡桩基的非线性行为。本项目研究成果深化了对斜坡与荷载方向协同合作用的超大直径风电桩基承载特殊和受力机理的认识，对指导海上超大直径风电桩基设计与计算，具有理论与实际意义。