地震波动入射方向对土石坝地震反应的影响研究

发布时间：2018-03-17 15:03

本文选题：土石坝　切入点：粘弹性人工边界　出处：《大连理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：目前土石坝抗震分析一般采用刚性边界模型,假定边界处各点的地震加速度相同,利用施加惯性力来实现地震动输入,本文称之为一致输入方法。该方法采用的是一个能量封闭的系统,在地震过程中,外行散射波无法透过边界,使边界上的反射波继续影响坝体,未能考虑无限地基的辐射阻尼作用。此外,随着坝体高度的增加,坝基的尺寸也随之增大,地震波动使大坝底部各点的振动存在着较大的相位差,行波效应的作用明显增强。从以上方面可以看出,传统的一致输入方法很难真实地反映出大坝的地震响应规律。大多学者在研究土石坝抗震问题时假定地震波沿垂直方向入射,然而对于近场浅源地震或者场地条件比较复杂的坝址区,地震波通常会以某个角度入射到地表,因此,采用合理的地震波动输入方法,研究地震波从不同方向入射对土石坝地震反应的影响是十分必要的。本文为综合考虑坝体和地基之间的相互作用、地基辐射阻尼和行波效应对坝体动力反应的影响,采用粘弹性人工边界及其相应的等效荷载地震动输入方法,成功模拟了地震波不同方向入射的问题,讨论了其对土石坝地震反应的影响。主要完成了以下工作： 1.采用上述地震动输入方法对一典型高土石坝模型进行地震反应计算,讨论了该方法在地基辐射阻尼及坝体与地基之间相互作用的模拟效果；从地震波频谱特性、坝高、加速度峰值和地基刚度等四个方面,探讨了该方法对高土石坝地震反应的影响。 2.针对一典型高土石坝有限元模型,分别计算了SV波和P波以不同角度从不同方向入射时坝体的动力反应。从坝顶加速度反应、坝坡动力稳定和坝体永久变形等方面,探讨了地震波入射方向和行波效应的影响。
[Abstract]:At present, the seismic analysis of the dam adopts the rigid boundary model, assuming the boundary points of the same seismic acceleration, using the inertial force applied to seismic input, this is called the uniform input method. This method is used in an energy closed system in the earthquake process, lay scattered wave cannot penetrate the boundary. The reflection on the boundary of the wave continues to influence the dam, failing to consider radiation damping effect of infinite foundation. In addition, with the increase of the height of the dam, the dam size increases, the seismic wave makes the vibration of each point in the bottom of the dam with larger phase difference, the effect of traveling wave effect is enhanced significantly. From the above aspects can be seen. Consistent with traditional input method is difficult to reflect the response of the dam earthquake.
Most scholars assume that the seismic wave incident along the vertical direction in the study of earth dam seismic, but for the near field of shallow earthquakes or site of complicated condition of dam area, the seismic wave is usually at an angle to the incident surface, therefore, the reasonable seismic wave input method, effects of seismic waves from different incident directions the seismic response is very necessary.
In this paper, considering the interaction between the dam and foundation, the influence of foundation radiation damping and traveling wave effect on the dynamic response of the dam, the viscoelastic artificial boundary and the equivalent load corresponding seismic input method successfully simulated earthquake wave with different incident directions, its influence on seismic response of earth rockfill dam is discussed mainly. The following work:
1. by using the method of earthquake input seismic response calculation of a typical high rockfill dam model, discusses the simulation result of the method is the interaction between the radiation damping of foundation and dam and foundation; from the spectral characteristics of seismic waves, dam height, peak acceleration and foundation stiffness in four aspects, discusses the influence of the reaction method the earthquake of high rockfill dam.
2. for a typical high rockfill dam finite element model, the dynamic response of SV wave and P wave at different angles from the different direction of incidence of the dam are calculated. The reaction from the horizontal acceleration, the dynamic stability of dam slope and dam permanent deformation etc., discusses the influence of incident angle of seismic wave and traveling wave effect.

【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV641;TV312

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