分层强剪切内波环境中柱体失稳机理研究

项目名称： 分层强剪切内波环境中柱体失稳机理研究

项目编号： No.51479058

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 水利工程

项目作者： 王玲玲

作者单位： 河海大学

项目金额： 84万元

中文摘要： 海港码头桩基及河口桥梁墩柱受非恒定、层化、强剪切环境流体作用，其稳定性与环境流体水动力特性及基础冲淤密切相关，失稳机理极为复杂。本项目拟运用海洋密度分层流研究中的内波理论，将近岸及河口桩柱稳定问题概化为分层强剪切内波环境中桩柱受力及基础冲淤问题，采用物理模型试验、数值模拟计算、现场监测和理论分析相结合的方法，对近岸及河口内波数学模型的建立，内波产生、传输、消亡过程，内波对柱体的作用规律及对柱基河床的冲淤效应进行系统研究，揭示层化强剪切环境流体中柱体失稳机理。在此基础上，以具有季节性分层特性的长江口南支为典型区域，建立内波-水动力-泥沙-结构桩柱耦合模拟模型，借助盐度、含沙量、水动力及地形监测资料，率定验证数值模型，探索多因素耦合作用下柱体稳定条件及失稳机理，提出剪切强度等环境要素与柱体失稳的响应关系。成果对提高近岸及河口建筑物桩柱安全有重要意义，可为相关设计规范与行业标准的修订提供支持。

中文关键词： 分层流；强剪切；内波；桩柱；失稳机理

英文摘要： The pile foundations in harbors and bridge piers in estuaries are affected by the unsteady, stratified and strong shear environment. The instability mechanism of the foundations is extremely complicated as the instability is closely related with the hydrodynamic characteristics of environmental flows as well as the foundation scouring and silting. In the present research, the stability problem of piles in off-shore regions and estuaries will be generalized as a problem of pile stress state, foundation scouring and silting in strong shear stratified flows under the internal wave in density stratified flows. A mathematical internal wave model in near shore regions and estuaries will be established based on the laboratory experiments, numerical simulations, in-situ monitoring and theoretical analysis. The generation, propagation and degeneration of internal waves, the corresponding impacts on cylinders, as well as the foundation scouring and silting will be systematically studied to reveal the instability mechanisms of cylinders in strong shear stratified flows. In the further study, the southern branch of the Yangtze estuary with seasonal stratification characteristics will be set to be a typical study region. A coupling model of internal wave, hydrodynamics, sediment and piles will be developed and verified with the in-situ salinity, sediment, hydrodynamic and geographic data. The stable conditions and instability mechanisms for cylinders under the multi-factor coupling situations will be explored and the relationship between the instability of cylinders and the environmental factors, such as the shear intensity, will be concluded. The research results have great significance on the improvement of the safety and stability for piles in coastal and estuarine constructions, and could provide theoretical support to the amendments of relevant design specifications and industrial standards.

英文关键词： stratified flow;strong shear;internal wave;cylinder;instability mechanism