【作者】 杨加智；

【导师】 朱岳明；

【作者基本信息】 河海大学 ， 水工结构工程， 2007， 硕士

【摘要】 本文在总结分析前人研究成果的基础上，论述了用有限元法计算非稳定渗流场的基本理论，并将其应用到实际工程中。文中主要做了以下工作：(1)通过变分原理，运用插值函数和等参变换推导了渗流微分方程的有限元法格式，建立了非稳定渗流数学模型，讨论了有限元方程求解的稳定性，介绍了本文所采用的求解大型稀疏方程组的基于对称逐步超松弛迭代的预处理共轭梯度法(SSOR-PCG)。(2)求解无压渗流场问题的关键在于确定渗流逸出面和自由面的位置，在分析目前常用的几种求解自由面方法的基础上，重点介绍了本文采用的求解有自由面渗流问题的固定网格的结点虚流量法，并通过算例说明该方法能实现无压渗流场的快速迭代求解。(3)非稳定渗流场数值求解中的自由面积分项很难精确处理，本文将曲面积分转换为在坐标平面上的积分来近似处理非稳定渗流的自由面边界，编制了非稳定渗流场有限元计算程序，并通过算例验证了程序的正确性。(4)遗传算法作为一种高效的全局寻优的方法，经过改进其局部寻优能力，能够作为渗流反分析的重要工具。本文结合非稳定渗流计算程序，运用改进的加速遗传算法编制了渗流问题的反分析计算程序，并对本程序进行了算例验证。(5)针对嶂山闸闸基的渗流“异常现象”，将可能引起这种“异常现象”的主要因素概化为特征参数变量，经过对闸基主要参数的反分析、渗流场的正分析以及计算结果的对比分析，搞清了该闸闸基渗流“异常现象”的具体成因，最后提出了经济可靠的工程加固处理方法。更多还原

【Abstract】 Based on the previous research findings in hydraulic engineering, the basic theories on caculating the unsteady seepage field with finited element method (FEM) are studied in this paper. The key contents involved are as follows:(1)Based on the theory of variation, the FEM form of seepage calculation is concluded by using interpolation function and isoparametric transformation, and the mathematical model of unsteady seepage is established. The solution stability of the FEM matrix is studied, and the symmteric successive over relaxation-precondition conjugate gradient method (SSOR-PCG) to solve the large-scale FEM equations is recommended.(2)After the several methods to solve this problem have been analyzed, the key issue in solving unsteady seepage problem is to identify the location of free table and outflow line. The nodal virtual flux method is used to solve the seepage problem with free table, and the validity of the method is proved by an example.(3)The approximate method is proposed by changing the surface integral to plane integral, because it is difficult to correctly deal with the integral about the free table. A program for solving the unsteady seepage field is written, and it is proved to be correct by an example.(4)As a effective method on seeking the reasonable result in complete region, the genetic algorithm (GA) could be a important tool in seepage conter-analysis, after being improved its partial search ability. A program for the seepage conter-analysis is written, based on the improved accelerating genetic algorithm (IAGA), combined with the program of solving the unsteady seepage field, and it is validated by a example.(5)The primary factors about the abnormal phenomenon of seepage in Zhangshan Lock are summed up as a series of characteristic parameter variable. The causes which bring the abnormal phenomenon are made clear by conter-analysis, seepage analysis and contrast analysis, and then some economical reliable processing measures are proposed.更多还原