海床对水表面波动态响应的研究

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题名	海床对水表面波动态响应的研究
作者	林缅
学位类别	博士
答辩日期	2000
授予单位	中国科学院研究生院
授予地点	北京
导师	李家春
关键词	波浪海洋土底床失稳海岸工程 water waves marine soil seabed instability ocean engineering
学位专业	流体力学
中文摘要	在设计各种各样的海工结构物时，必须考虑海洋波浪引起的海床变形乃至失稳问题。本文旨在通过波浪作用下海洋土动态响应的研究，对海洋土在各种加载条件下所呈现的动力学特点做全面细致的了解，揭示一些现象的力学机制，为工程设计提供可参考的科学依据。系统地研究了线性波和有限深底床相互作用下底床土层的动态响应。应用弱非弹性多孔介质模型，针对波浪衰减、底床中应力场分布以及土骨架位移等问题，进行了详细地分析。预测了在不同的波参数和土参数下，土床可能发生破坏的最大深度，分别分析了粗，细砂土床中渗滤作用和土颗粒之间的库仑摩擦对底床稳定性所带来的影响。通过对不同土质底床在波浪作用下所表现的动态特征，讨论了粉土床发生共振液化的力学机制，提出了共振液化发生的必要条件。考虑了非线性波和弱非弹性多孔介质的耦合，推导了在弱非弹性多孔介质上传播的浅水波方式，得到了依赖于土参数的椭圆余弦波波面方程，以及土床应力场和土骨架位移的关系式。根据浅水波相速度和衰减率的计算结果，分析了浅水波在不同土质底床上的传播特性，具体讨论了在椭圆余弦波作用下土床中孔隙水压力随波高和周期的变化关系，通过和线性波结果的比较分析，给出了该理论的适用范围，并得到他人实验结果的验证。分析了短峰和底床相互作用所引起的防波提失稳问题。给出了非完全反射防波堤前土床中的应力场分布，对短峰波所引起的底床液化势及剪切破坏进行了详细地讨论。针对不同土质底床，计算了底床最大破坏深度以及破坏区域随加载波周期、水深及入射角的变化关系。参照实际工程，讨论了考虑防波堤自重情况下防波堤的失稳，给出了敏感区域。
索取号	29934
英文摘要	The deformation and instability of seabed subjected to water surface wave loading constitute an important factor for engineers to consider in planning various offshore facilities The present thesis aims at understanding the characteristics of marine soil and revealing the mechanism of certain phenomena by investigating dynamic response of seabed to water surface waves, thus providing useful parameters and scientific foundation for engineering design. To begin with the dynamic response of seabed owing to the interaction between linear waves and finite depth seabed has been studied systematically. Based on the weakly non-elastic porous medium model, the wave damping and the distribution of stress and displacement in soil skeletal frame have been calculated carefully. In most cases, the maximal failure depths are predicted. And then the effects of permeability and the Coulomb friction for coarse and fine sandy seabed on its instability have been analyzed respectively. By examining the soil dynamic characteristics under water wave loading, the mechanism of resonant liquefaction occurring in silty seabed is explored. A necessary condition for such kind of liquefaction to take place is then proposed. In view of the coupling between nonlinear waves and weakly non-elastic porous medium, a governing equation is subsequently obtained for shallow water wave running over the porous medium. In the meanwhile, the Cnoidal-wave profile and the distribution of stress and displacement in soil skeletal frame have been established. A cording to the numerical results of phase velocity and wave damping, the propagating properties of shallow water waves are demonstrated. And the variations of pore pressure with water depth and wave period have also been discussed. By referring to the linear theory, the appropriate regime of wave parameters for the nonlinear theory to apply is indicated. A good agreement in pore pressure exhibited between the results of nonlinear theory and the available experiments further validates the present model. The instability of breakwater induced by interaction between short-crest waves and seabed has been addressed in the last chapter. An analytical solution for the stress produced by partly reflected in travelling wave in the seabed in front of a breakwater is provided. And then, the liquefaction potential and shear failure due to short-crest waves are investigated. For typical kinds of seabed, it is found that the maximal failure depth and region vary with wave loading period, water depth and incident angle. As a realistic example, the effects of breakwater deadweight on the instability are finally examined to show its sensitive regions.
语种	中文
学科主题	流体力学
公开日期	2009-04-13 ; 2009-08-25
出处	[博士论文].北京.中国科学院力学研究所,2000
内容类型	学位论文
源URL	[http://dspace.imech.ac.cn/handle/311007/23386]
专题	力学研究所_力学所知识产出(1956-2008)
推荐引用方式 GB/T 7714	林缅. 海床对水表面波动态响应的研究[D]. 北京. 中国科学院研究生院. 2000.