【作者】 李晓军；

【导师】 辛全才；

【作者基本信息】 西北农林科技大学 ， 水工结构工程， 2008， 硕士

【摘要】 高拱坝体形设计是关系到大坝安全和经济的关键技术问题。高拱坝设计对地质条件的适应性要求越来越高,优化设计时要考虑到复杂地质条件的影响,最好采用已被工程界普遍接受的有限单元法等现代计算方法。这对以多拱梁法为主的拱坝优化设计体系提出了新的挑战,除了需要解决不同条件、不同拱坝参数的全自动计算问题,还需要解决由于结构计算的时间增加所带来的优化计算的可行性和效率问题。本文的主要工作有:首先对国内外拱坝优化设计及其相关领域研究现状进行了总结,详细介绍了高拱坝优化设计的数学模型和优化方法。提出了基于有限单元法的高拱坝优化设计的基本体系。然后基于线弹性有限元计算理论和数值方法,利用大型有限元软件ANSYS的参数化语言APDL编制程序,实现了拱坝参数化几何模型和有限元模型的自动建立;施加温度荷载作稳定温度场分析,然后施加自重,水压力,泥沙压力和温度场分析结果文件进行耦合分析求解;同时利用优化模块,对水平拱圈拱轴线分别为抛物线、椭圆线和对数螺旋线三种曲线的拱坝体形进行了优化分析。以拱冠梁几何特征参数和水平拱圈几何特征参数为设计变量,其中设计变量多达32-40个,以大坝体积为目标函数,考虑几何约束、应力约束和稳定约束等约束条件,在坝体应力和稳定满足规范的前提下,寻求经济实用的体形。优化过程由计算机软件自动执行和控制,减少以往设计过程中不断重复所消耗的时间。结果表明该程序可靠性强、效率高、收敛性稳定。接着本文针对拱坝有限元等效应力作了相应的讨论,推导出了拱坝有限元等效应力计算公式,编写出了拱坝有限元等效应力在ANSYS中实现计算的程序。实现了以等效应力作为应力约束条件进行拱坝体形优化。同时,针对高拱坝有限元等效应力控制标准作了初步的探讨。基于有限单元法软件进行拱坝体形优化设计,其建模、加载、求解及优化计算等一系列工作都可以由程序自动完成,求解效率高,过程简单,智能化程度高。强大的后处理功能可以多种图表给出计算结果,对设计者全面了解坝体应力和位移提供了极大的方便。最后,以黄河拉西瓦为例,分别作了三种曲线体形优化,然后对三种体形做出了综合性评价。作为理论在实际工程当中的应用和实践对理论的检验。更多还原

【Abstract】 The shape design of high arch dam is the key technique for the safety and economy of the dam. The adaptability of arch dam to geology is better and better, when the influence of complicated geology is considered, the best way is to use modern calculating optimization design which is widespread now, that is a new challenge to old optimization design system of crown cantilever analysis. The modern calculating optimization design not only needs to solve calculation problem of the different condition and different arch dam parameter full-automatically, but also needs to consider the possibility and the efficiency which were caused by the increments of calculation time.The main tasks of this paper are as follow:Firstly, the situation of optimization design of arch dam and the related realm at present is introduced; the mathematics model and methods of optimization design in high arch dam were presented in details, and then put forward optimization design method of high arch dam based on finite element method (FEM).Secondly, based on the linear elastic finite element calculating theory and mathematics method, the geometry and finite element model of high arch dam are established by the parameter design language(APDL) of the large-scale common finite software ANSYS, and A Steady-State Thermal Analysis is executed by application the temperature load. Applying the water load, deadweight load, and sand load, Reading the results of thermal analysis, to execute the Coupled-Field analysis of thermal-structural solution. Meanwhile optimizing the high arch dam of the parabola, the ellipse and the logarithmic spiral respectively by using optimal module of the finite element software ANSYS. In this paper, the geometrical characteristics parameter of high arch dam were taken as the design variables which were combined of totally 32-40 parameters, dam volume is taken as objective function, considering the restraint condition of geometric, stress and steady condition. The economic and practical shape is searched out in the condition of the dam’s stress and stability against sliding all satisfying the require of criterions. The course of optimization design can be automatically carried out and controlled by the computer software, which reduces the time consumed in the repeated design process. The result proves that this procedure is highly reliable, skyscraping efficient and stability convergent. Then this paper discussed correspondingly the arch dam’s equivalent stress of finite element, educed the expressions of the arch dam’s equivalent stress of finite element, programmed the procedures of arch dam’s equivalent stress of finite element based on the software ANSYS. The optimal design for shape of arch dam using equivalent stress of finite element as stress restraint condition is carried out.The optimal design of arch dam based on the finite element method, for a series of work of it such as modeling, load application, solution and optimal calculating all can finish automatically, so it has high efficiency of solution, compact process and high degree of intelligence. The strong after-treatment ability of the software makes the result observing much more convenience and immediacy by kinds of charts, which offer convenience for architect to comprehend the stress and displacement of arch dam.Lastly ,as a practical example, three curve shape of the Laxiwa arch dam were made Optimization respectively, then make a comprehensive evaluation of the three shape optimal designs to be a practical test for the theory.更多还原