【作者】 朱立波；

【导师】 邢述彦；

【作者基本信息】 太原理工大学 ， 水利水电工程， 2010， 硕士

【摘要】 水电站钢衬钢筋混凝土压力管道的独特优势是钢衬与外围钢筋混凝土联合受力,同时允许在内水压作用下混凝土出现若干径向裂缝以发挥钢材强度。与压力钢管相比,在相同荷载条件下,它除了可以减薄钢衬,降低对板材加工、安装的难度并经济实用,还可降低发生事故的风险。这种管道布置在混凝土坝的下游坝面,对大坝整体结构削弱较少,又能避免坝体混凝土浇筑与钢管安装之间的施工干扰,已被国内外水电站工程设计所广泛采用。随着我国水电事业的不断发展,水电工程的规模日益庞大,水电站的压力管道的PD值也不断增大,作为水电站建筑关键性结构物,其运行安全稳定及结构形式直接关系到整个电站的安全稳定运行,关系到电站建设的投资,因此,准确地分析计算压力管道的应力状态,合理地选择钢衬厚度及外包混凝土的配筋率,具有十分重要的意义。本文在前人研究的基础上根据钢衬钢筋混凝土压力管道设计规范、结合结构模型实验成果和非线性分析理论,建立钢衬钢筋混凝土压力管道计算模型,使用先进有限元软件ANSYS对钢衬钢筋混凝土压力管道进行非线性分析,从而得到钢衬钢筋混凝土压力管道的应力分布特点和破坏机理;对钢衬钢筋混凝土压力管道的应力发展历程作了具体的分析;在保证结构安全性和混凝土开裂不超过允许值的前提下,对管道进行了优化设计。研究结果表明:1.运用ANSYS软件对水电站压力管道进行三维非线性有限元计算可以考虑混凝土与钢筋的交互作用,多轴应力状态下的材料特性,混凝土的开裂特性等因素,计算结果较经典理论分析更能反映实际。2.钢衬钢筋混凝土管道断面型式对管道的应力分布有很大影响,采用不同的计算有限元模型所得的结果可能相差很大。3.在钢衬钢筋混凝土压力管道结构优化设计中,约束条件众多,要全面考虑各种约束条件,遗漏或不恰当地规定约束条件,也会导致得不到最优解。钢材用量优化时,不能一味地追求尽量发挥钢材的作用,理论上必须同时保证由安全系数计算所得钢材折算厚度和以满足钢筋应力表达的混凝土开裂条件的钢材配置才是对结构有利的。4.结构优化时,用轴对称圆环模型进行有限元分析,可以方便地提取状态变量参数,所得结果比较可靠。经过优化,截面设计变量已最大程度的满足混凝土表面裂缝的限制要求,但考虑到方圆形模型腰部控制截面外环钢筋有可能出现较大拉应力而较早屈服,为防止最外层钢筋较早屈服,方圆形模型腰部控制截面(约-30°～35°)处还需多布置一些钢材。更多还原

【Abstract】 Unique advantage of steel liner-reinforced concrete penstocks of hydropower stations is a kind of combination structure, it permit occuring radial crack in the concrete tube to maximizing Stress intensity of steel. Compared with penstock, it can reduce the thickness of steel liner, the sheet processing, installation difficulty, risk of accidents. Also it has economical use. This penstock is located on the downstream surface of concrete dam. The layout can less weaken the whole structure of the dam and avoid interruption between concrete pouring and penstock installation. The layout has been widely used at home and aboard. With the unceasing development of water and electricity enterprise of our country, daily increasing at scale of hydropower station in China, PD value of penstock is also growing. As a key structure building of hydropower station, operation security and structure stability of penstock are directly related to operation security and structure stability of the whole station. So it is of vital importance to analyze the stress state of penstocks accurately, select the thickness of steel liner and the ratio of concrete encasement einforcement reasonably.In this paper, the structure model of double steel liner-reinforced concrete penstocks is built and nonlinear analyzed by software named ANSYS and gained the structure style’s echanical character and destroy mechanism of steel liner-reinforced concrete penstocks and analyzed its stress development process and carried on the optimization design using the optimized module provided by ANSYS in the favor of APDL,which is based on design principle, research fruits, model test and nonlinear analysis fruits of steel liner-reinforced concrete penstocks. Under the premise of ensuring structural safety and cracking value of concrete not more than allowable value, this paper does the optimization design to penstock. The results show that:1. Analyzing finite element analysis model of steel 1iner-reinforced concrete penstocks by ANSYS can consider the factors: concretes and steel bar correlation, materials behavior under multiple spindle stress condition, concretes dehiscence characteristic and so on. The results are better than the theory analytic method in engneer practice.2. Section forms of steel liner-reinforced concrete penstocks of hydropower stations have great influence on its stress distribution. And the results of the different element calculation models might differ greatly.3. In the process of optimizational design of steel- lined reinforced concrete penstocks of hydropower stations, Constraints are many and must be fully considered. It could not get optimal solution if constraints be omitted and incorrectly limited. While optimizing the amount of steel, maximizing Stress intensity of steel is unsuitable. Theoretically, it must be suitable for both the thickness of steel products determined by single security factor and concrete cracking conditions determined by stress intensity of steel products, which are favorable to structure security.4. Using the axisymmetric ring model during finite element analysis can easily draw the parameters of state variables when optimizing structure. The results obtained are more reliable. After structure optimization, the design variables of the section meet the restriction requirements of concrete surface crack to the maximum extent. However, the outer steel bar of the control section on waist of the square-round model probably appears the higher tensile stress and earlier yields. To prevent earlier yielding of the outer steel bar, there needs more steel products on the control section (about -30°～35°)on waist of square-round model.更多还原