渗流与地震耦合作用下土石围堰稳定性分析

发布时间：2018-07-18 13:25

【摘要】：土石围堰是保证水电站等其他水下项目干地施工所建的临时性挡水建筑物，其安全问题不仅关系到主体工程的施工进度和施工安全，而且还关系到下游人们的生命安全和财产安全。在地震区土石围堰中的渗流问题以及抗震问题是引起土石围堰失事的两个重要因素。土石围堰抗震稳定性分析的目标，是根据工程破坏特征和破坏机理提出合理抗震设计方法和抗震措施。本文结合金沙江中游某大坝上游土石围堰工程，运用flac3d数值软件进行分析，研究了土石围堰的动力反应特性及破坏机理，，论文的主要研究内容如下：（1）系统地论述了flac3d的动力以及动力与渗流耦合的计算原理和方法，并与有限元结果相比较，结果表明：运用flac3d进行模拟土石围堰地震反应是合理的。（2）模拟了土石围堰在动力荷载作用下的变形情况，分析了其动位移、加速度变化规律及应力分布规律等动力反应特性，以及堰体可能出现破坏的位置及整个堰体的稳定性，结果表明：堰体的竖向位移主要集中在堰顶下方37m处；堰体的水平位移明显大于基础的水平位移；堰体的地震破坏是先从堰顶或堰面开始。（3）模拟了土石围堰在稳定渗流和动力荷载耦合作用下的变形情况,分析了其动位移、加速度变化规律及其应力分布规律等动力反应特性，从而分析堰体在稳定渗流与动力耦合作用情况下的稳定性，结果表明：竖向位移和水平位移均以土工膜为分界线；必须在堰体迎水面堰顶附近17m范围内采取局部加固。（4）模拟了土石围堰在非稳定渗流和动力荷载作用下的变形情况，分别模拟并分析了水位变化速度为缓变和骤变的情况下与动力荷载共同作用时的动位移分布规律等动力反应特性，分析了在水位上升和水位下降非稳定渗流与动力耦合作用情况下堰体的稳定性，结果表明：无论是水位上升或者是下降，与稳定水位下相比竖向位移和水平位移最大值增大幅度都相当的明显，在水位变化为缓变时竖向和水平位移最大值增大幅度较大，之后水位变化为骤变时幅度有所降低。
[Abstract]:Earth-rock cofferdam is a temporary water retaining structure which is built by dry land construction of other underwater projects such as hydropower stations. Its safety is not only related to the construction schedule and construction safety of the main project. And also related to downstream people's lives and property safety. Seepage and seismic problems in earth-rock cofferdam in earthquake area are two important factors that cause the failure of earth-rock cofferdam. The purpose of seismic stability analysis of earth-rock cofferdam is to put forward a reasonable seismic design method and seismic measures according to the damage characteristics and failure mechanism of engineering. Combined with the earth-rock cofferdam project in the upper reaches of a dam in the middle reaches of the Jinsha River, the dynamic response characteristics and failure mechanism of the earth-rock cofferdam are studied by using flac3d numerical software. The main contents of this paper are as follows: (1) the dynamics of flac3d and the calculation principle and method of coupling of dynamic and seepage are discussed systematically, and the results are compared with the results of finite element method. The results show that it is reasonable to use flac3d to simulate the seismic response of earth-rock cofferdam. (2) the deformation of earth-rock cofferdam under dynamic load is simulated and its dynamic displacement is analyzed. The dynamic response characteristics such as acceleration variation law and stress distribution law, the position where the Weir body may be destroyed and the stability of the whole Weir body are discussed. The results show that the vertical displacement of the Weir body is mainly concentrated at 37m below the top of the Weir. The horizontal displacement of the Weir is obviously larger than that of the foundation, and the earthquake failure of the Weir begins from the Weir top or the Weir surface. (3) the deformation of the earth-rock cofferdam under the coupling of steady seepage and dynamic load is simulated. The dynamic response characteristics, such as dynamic displacement, acceleration change and stress distribution, are analyzed, and the stability of Weir under the condition of steady seepage and dynamic coupling is analyzed. The results show that both vertical displacement and horizontal displacement are separated by geomembrane. It is necessary to take local reinforcement within 17m near the top of the Weir. (4) the deformation of earth-rock cofferdam under unsteady seepage and dynamic load is simulated. The dynamic response characteristics of the dynamic displacement distribution under the condition of slow and sudden change of water level and dynamic load are simulated and analyzed respectively. The stability of Weir is analyzed under the condition of unsteady seepage and dynamic coupling of water level rising and water level decreasing. The results show that whether the water level is rising or falling, The maximum values of vertical displacement and horizontal displacement are quite obvious compared with those under steady water level. The maximum values of vertical and horizontal displacements are larger when the water level changes slowly and then decreases when the water level changes to sudden change.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV551.31

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