混凝土坝水管尺度级别温度场模拟研究

发布时间：2018-10-25 13:47

【摘要】：混凝土坝,尤其是混凝土拱坝的温度控制问题是其施工期的核心关注点。冷却水管作为最为常见的温度控制措施,将在混凝土内部产生较为复杂的温度场分布情况,一种适用于这种精细化温度场的计算方法将为实现智能化温度控制提供良好的理论基础与技术支撑。但现有研究仍难以达到在不特殊建立水管单元、不加密有限元网格的基础上,实现对水管附近真实温度场的正确计算。论文以此目标为研究导向,开展了系统性的研究工作,提出了含水管细尺度温度场的计算方法,并最终建立了一套完整的、快速的、正确的、可用于工程级别的大体积混凝土仿真分析平台。本文的主要内容包括:(1)提出了含冷却水管的混凝土不连续温度场的求解方法。通过对理论推导给出的非线性解空间的捕捉,构造了适应于该问题的扩充形函数;针对单元内部含有第一类边界条件的情况给出了点源式第三类边界条件的转化方法;并对含水管问题的求解域简化、单元内含有不连续场的积分方案以及时间域的积分方法等方面进行了详细的研究与讨论。(2)提出了无网格依赖性的水管空间离散建模与三维求解方法。基于计算几何提出了三维富集单元的快速搜索判识算法,实现了在不考虑水管信息的有限元网格中自动得到水管在混凝土中位置的目的;给出了包括单管斜穿单元、管铺设在单元底面、多管穿越单元等多种复杂空间位置关系下的积分方案与边界条件修正算法;结合水冷函数算法与管壁换热递推算法给出了沿程水温的计算方法。(3)综合粗、细尺度计算方法与智能化前、后处理方法,建立了大体积混凝土温度场仿真平台。基于等效冷却效果的思想,利用麦克劳林级数展开推导了多层水管的等效导温系数,实现了利用同一套粗网格对不同水管铺设方案下大体积混凝土温度场的求解;基于计算几何给出了混凝土坝复杂、动态变化的温度边界条件智能化探测算法;建立了大规模工程有限元自动化后处理平台,解决了人工后处理的困难;基于第5代HTML标准提出了易于信息传播、便于多方共享的有限元成果互联网共享方法。
[Abstract]:The temperature control of concrete dams, especially concrete arch dams, is the core concern during construction. As the most common temperature control measure, the cooling water pipe will produce more complicated temperature field distribution in the concrete. A calculation method suitable for this kind of fine temperature field will provide a good theoretical basis and technical support for the realization of intelligent temperature control. However, the current research is still difficult to achieve the correct calculation of the real temperature field near the water pipe on the basis of no special water pipe element and no encryption finite element mesh. In this paper, a systematic research work has been carried out, and a method for calculating the temperature field of water pipes on a fine scale has been put forward. Finally, a set of complete, fast and correct methods have been established. It can be used for mass concrete simulation and analysis platform of engineering grade. The main contents of this paper are as follows: (1) the solution of discontinuous temperature field of concrete with cooling water pipe is proposed. By capturing the nonlinear solution space derived from the theoretical derivation, the extended form function suitable for the problem is constructed, and the transformation method of the point source type third type boundary condition is given for the case of the first kind of boundary condition in the element. And the solution domain of the water pipe problem is simplified, The integral scheme with discontinuous field in the element and the integration method in time domain are studied and discussed in detail. (2) A mesh-independent discrete modeling method for water pipe space and a three-dimensional solution method are proposed. Based on computational geometry, a fast search and recognition algorithm for 3D enrichment element is proposed, which realizes the purpose of automatically obtaining the position of water pipe in concrete in finite element mesh without considering the information of water pipe. The integral scheme and boundary condition correction algorithm of pipe laying on the bottom surface of the element and the multi-pipe crossing element are given, and the calculation method of the water temperature along the course is given by combining the water cooling function algorithm with the heat transfer recursive algorithm of the pipe wall. (3) the calculation method of the water temperature along the course is given. The simulation platform of mass concrete temperature field is established by the method of fine scale calculation and the method of intelligent pre-and post-processing. Based on the idea of equivalent cooling effect, the equivalent temperature conduction coefficient of multilayer water pipe is deduced by using McLaughlin series expansion, and the temperature field of mass concrete under different water pipe laying schemes is solved by using the same coarse grid. Based on computational geometry, an intelligent detection algorithm for complex and dynamic temperature boundary conditions of concrete dams is presented, and a finite element automatic post-processing platform for large-scale engineering is established, which solves the difficulty of artificial post-processing. Based on the fifth generation HTML standard, an Internet sharing method of finite element results is proposed, which is easy for information dissemination and multi-party sharing.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV544;TV642

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