拱坝瞬态热结构的受力分析

发布时间：2018-07-10 14:05

本文选题：ANSYS + 瞬态荷载　；参考：《昆明理工大学》2014年硕士论文

【摘要】：在拱坝中,其温度荷载是这种超静定结构的基本荷载之一,由温度变化从而引起相应的温度应力对拱坝的影响很值得研究。拱坝的体型是比较单薄的,对外界空气及水的温度的变化都是比较敏感。本文应用热传导理论和热结构耦合理论以及三维有限元法。以空心球为小例子,推导其在定解条件下受到外力以及瞬态变化的温度作用下,温度应力耦合场的计算公式。用数学软件Matlab对推导出来的理论解进行计算,再用有限元通用软件ANSYS对同样条件下的模型进行计算,通过两者结果的对比,验证了用ANSYS软件对瞬态的热结构耦合问题进行计算的可行性。并对空心球模型进行不同网格尺寸的划分,把得到的数值解与推导计算出的解析解进行对比分析,当划分网格的尺寸为空心球厚度的五分之一的时候,温度和应力的相对误差控制在5%左右。由于空心球和拱坝的结构具有相似的特点,要计算的拱坝的坝底厚度也是和空心球的厚度是一样的尺寸,可以认为其网格划分为更复杂的拱坝提供依据。从空心球中网格划分的方式推广到拱坝上,在ANSYS软件中采用和空心球同样的单元进行热结构的直接耦合分析,引入—参数——坝体结构总的应变能,通过对十二个月拱坝在瞬态温度荷载作用下的受力分析,得到在温降时期,拱坝最不利荷载滞后最低温度为15～20天,而在温升时期,拱坝最不利荷载滞后最高温度5-10天,即本文研究的某高拱坝最不利情况的时间就是在二月初到二月零五天间和七月零二十天到七月二十五天间。坝体最大径向位移和气温的关系是呈反相关的,温度升高,最大径向位移减小,温度降低,坝体最大径向位移增大。最后通过用有限元分析数值解的精度分析,估计出应变能的准确解,通过比较十二个月中,用空心球推广到拱坝上的网格划分得到的应变能与估计的应变能的准确解的相对误差,验证空心球小例子中的划分网格的尺寸的在拱坝中的可行性。
[Abstract]:In the arch dam, the temperature load is one of the basic loads of the statically indeterminate structure. The influence of the corresponding temperature stress on the arch dam caused by the temperature change is worth studying. The arch dam is thin and sensitive to changes in air and water temperatures. In this paper, the heat conduction theory, thermal structure coupling theory and three-dimensional finite element method are applied. Taking the hollow sphere as a small example, the formula for calculating the thermal-stress coupling field is derived under the condition of the fixed solution and the transient change of temperature. The mathematical software Matlab is used to calculate the derived theoretical solution, and the finite element general software ANSYS is used to calculate the model under the same conditions. The feasibility of using ANSYS software to calculate the transient thermal structure coupling problem is verified. The hollow sphere model is divided into different mesh sizes, and the numerical solution is compared with the calculated analytical solution. When the mesh size is 1/5 of the thickness of the hollow sphere, The relative error of temperature and stress is about 5%. Because the structure of hollow sphere and arch dam have similar characteristics, the thickness of the bottom of arch dam to be calculated is the same size as the thickness of hollow sphere, so it can be considered that the mesh of the arch dam can be divided into more complex arch dams to provide the basis. The method of grid division in hollow sphere is extended to the arch dam. The thermal structure is directly coupled with the same element as the hollow sphere in ANSYS software, and the total strain energy of the dam structure is introduced. Through the stress analysis of the 12 month arch dam under the action of transient temperature load, it is obtained that the lowest temperature of the most unfavorable load lag is 1520 days in the temperature drop period, while in the temperature rise period, the maximum temperature lag of the most unfavorable load in the arch dam is 5-10 days. That is to say, the worst time of a high arch dam studied in this paper is from the beginning of February to February and from February to February and from 20 days to 25 days in July. The relationship between the maximum radial displacement of the dam body and the temperature is inversely correlated, the temperature increases, the maximum radial displacement decreases, the temperature decreases, and the maximum radial displacement of the dam body increases. Finally, by using the accuracy analysis of the numerical solution of finite element analysis, the accurate solution of strain energy is estimated. The relative error between the exact solution of the strain energy and the estimated strain energy obtained by the mesh division of the hollow sphere on the arch dam is extended to verify the feasibility of the mesh size of the hollow sphere in the arch dam.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV642.4;TV315

【参考文献】