波致非均匀海床累积响应及其与单桩耦合动力机制研究

Mono-pile foundation is widely adopted in the construction of marine structures, and its irrational design may cause serious accident or tragedy. The dynamic wave loading would induce seabed residual response and instability, which is one of the key factors leading to the failure of mono-pile foundation. In addition, the long-time cyclic motion of mono-pile would lead a 3D non-homogeneous soil properties within its surrounding seabed, and this could significantly affect wave-induced seabed and mono-pile response. The previous studies were limited to homogeneous seabed and elastic soil theory, which neglected the non-homogeneous seabed response and soil elasto-plastic behavior. This project aims to investigate the wave-pile-seabed (non-homogeneous) interaction by theoretical analysis, laboratory experiment and numerical simulations. This includes: (1) wave induced seabed residual response around mono-pile foundation; (2) Effects of the non-homogeneous soil properties on the seabed residual response around mono-pile; (3) interaction behaviors between wave, mono-pile and non-homogeneous seabed. This project emphasizes on the mechanism of wave induced seabed elasto-plastic behavior and its interaction with mono-pile foundation, the effects of non-homogeneous soil on the interaction behavior between seabed and mono-pile. Fully interaction model between wave, non-homogeneous seabed and mono-pile would be established, for the accurately assessment of wave induced non-homogeneous seabed residual response and its dynamic interactions with mono-pile. This project would make efforts on the protection of the mono-pile foundation from damage/failure caused by the wave-induced instability of a non-homogeneous seabed.

海工结构物较多使用单桩基础支撑，单桩设计不当可能导致灾难性事故。波浪作用下海床累积响应及失稳是单桩破坏的主要原因之一。另一方面，单桩因长期循环荷载作用其周围海床呈现的三维非均匀分布特征，是影响海床和单桩响应的关键因素。前人研究大都局限于均匀海床和土体微小弹性变形，难以求解波致非均匀海床弹塑性变形过程。本项目采用室内试验、数值模拟和理论分析相结合的研究方法，关注波浪-单桩-非均匀海床相互作用过程，具体包括：1）三维波浪环境下单桩周围海床累积响应机制；2）非均匀土体对海床累积响应的影响机制；3）波浪-单桩-非均匀海床动力耦合机制。重点解决复杂波浪荷载下弹塑性海床与单桩的耦合响应机制、土体非均匀特性对单桩-海床动力系统的影响机制等关键科学问题，在此基础上建立波浪-单桩-非均匀海床强耦合计算模式，阐明波致非均匀海床累积响应及其与单桩耦合动力机理。本项目成果可为保障海工结构物基础安全提供科学依据。

波浪作用下海床液化和冲刷与结构物基础稳定性密切相关，一直是海岸工程领域的关注重点。在实际海洋地质环境下，海床土体特性往往是非均匀分布的。前人研究大都局限于均匀海床和瞬时海床响应过程，忽略了波致非均匀海床累积响应以及对海床液化和冲刷过程的影响机理。本项目采用室内试验、数值模拟和理论分析相结合的研究方法，研究波致非均匀海床累积液化机理，非均匀土体对单桩周围海床累积响应的影响机制，和海床冲刷过程对单桩周围海床动力响应的影响机制，建立了波浪作用下非均匀海床瞬时和液化耦合响应新理论，开发了三维波浪-非均匀海床-结构物耦合响应数值模型，阐明了非均匀海床特性、海床冲刷过程对单桩周围动力响应及液化的影响。本项目成果为海岸工程桩基础保护提供技术支持。