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为探讨海上风机在风、浪等水平往复循环荷载下大直径单桩基础的循环弱化特性,设计了稳定输出长期循环荷载的机械加载装置,开展了软黏土中长期水平循环荷载下海上风电大直径单桩基础和传统长桩基础的模型试验对比研究。根据API给出的骨干曲线和Masing二倍准则构建循环荷载下的p-y(荷载-位移)曲线,并借鉴前人工作,采用累积塑性应变描述软黏土的不排水抗剪强度弱化,提出了分析大周数水平循环荷载下单桩基础循环弱化的理论方法。该方法将循环荷载次数、幅值等外界条件与桩周土体的循环弱化特性建立联系,以适应海洋环境复杂多变的水平循环荷载形式。通过模型试验和理论研究认为,大直径单桩基础因刚度较大,在同样的水平力循环荷载条件下,其抵抗循环荷载的能力明显优于传统长桩。在海上风机大直径单桩的设计中采用基于黏土残余强度的循环后稳定水平承载力更为合理。
In order to discuss the cyclic weakening characteristics of offshore wind turbines under large horizontal single-pile foundation subjected to cyclic reciprocating loads such as wind and waves, a mechanical loading device is designed to stabilize long-term cyclic loading. The large- Contrastive study of model tests on single pile foundation and traditional long pile foundation. According to the backbone curve and Masing double criterion given by the API, the py (load-displacement) curve under cyclic loading is constructed. Based on the previous work, the cumulative plastic strain is used to describe the undrained shear strength weakening of soft clay. The theoretical method of cyclic weakening of single pile foundation under horizontal cyclic loading. In this method, the external conditions such as the number and amplitude of cyclic loads are related to the cyclic weakening characteristics of soils around the pile so as to adapt to the complex and ever-changing horizontal cyclic loading of the marine environment. Through model tests and theoretical studies, it is concluded that the larger diameter single pile foundation is more resistant to cyclic loading than traditional long piles under the same horizontal cyclic load due to its high stiffness. It is more reasonable to adopt the cyclic stable horizontal bearing capacity based on the clay residual strength in the design of large diameter single pile of offshore wind turbines.