【作者】 沈怀至；

【导师】 李振富；

【作者基本信息】 天津大学 ， 水利水电工程， 2004， 硕士

【摘要】 水电站蜗壳组合结构具有复杂空间空腔结构和三向受荷载条件，任何弹性力学的解析答案都无法精确的给出。通过介绍蜗壳设计型式，了解其发展趋势，据此分析蜗壳的研究方法，阐述各种设计型式的不同研究方法。平面应变或应力问题要求在垂直于平面的方向上不产生应变或应力及所受荷载平行于平面，故简化为平面问题只是在计算机尚未发展到一定程度下的一种尝试，是对简化的杆件系统计算方法的初步深化。模型实验对实际设计实体按一定比例进行模拟，将试验成果运用到实际生产中，这是今后主要研究方式一种。三维有限元计算真实地模拟了设计结构和受荷载条件，是采用计算机研究的重要方式，也是蜗壳研究另一种主要方式。本论文就是采用该方法对蜗壳结构进行三维仿真，计算成果说明该方法具有很高的仿真性、使用性及较高的经济效益，可以有效地解决工程实际问题。垫层材料应力应变试验可以了解不同材料的变化特征，分析在各自的应力区间中的应变范围。通过设定不同试验的环境，研究各种环境参数对应力、应变关系的影响。材料试验资料研究表明，三种材料中高压聚乙烯低发泡塑料优点显著，可为实际工程采用。垫层厚度受诸多因素影响，通过改变其厚度研究外包混凝土的应力和位移变化规律，了解厚度对应力、位移控制程度。经过对混凝土和钢衬直接联合作用以及30mm、40mm、50mm厚度垫层的分析，获得了定量的应力数据、位移量，不仅解决了工程设计配筋，而且为选择合理垫层厚度提供客观依据。垫层包角的变化直接影响其周边的应力和位移，尤其在变化部位影响更为显著，可一定程度反映外包混凝土中薄弱部位应力对垫层铺设范围灵敏程度。垫层弹性模量是其关键性力学指标，它直接影响到内水压力传递比，是该种蜗壳设计型式的重要因素，在计算模型中按不同垫层厚度下各种弹性模量进行计算，可以得到各种相应的应力数据，可描述应力与弹性模量定量的对应关系，为具体水电站工程设计和研究提供根据。通过建立局部三维模型和选取典型断面，分析在各种三向荷载作用下应力及位移，并与整体三维模型计算结果进行对比，可获得两者之间对比关系，为工程的可研、初设阶段简化计算提供理论。平面有限元计算，可以为了解具体工程条<WP=4>件下规程规范中采用的杆件系统计算精确程度，检查平面计算与三维整体模型成果的误差。将单一外载（内水压力）作用于三维整体模型，分析该荷载对外包混凝土中的总应力、总位移提供的分量，为各种荷载作用下的应力叠加提供应力分量，也可以间接分析其它荷载的影响程度。更多还原

【Abstract】 The composite construction of the shell-metal spiral casing in hydroelectric power station is a complex three-dimensional space structure with the three dimensional loading conditions，any result obtained from mechanics of elastic does not precisely describe its stress characteristics. By introducing model of spiral casing designing ，research methods on it is analyzed by knowing developing trend，further expounding different methods on models. Problems on plane strain or stress require no strain or stress at the direction of vertical to plane and loads parallel to the plane，so that the complex three-dimensional space structure simplified as plane during period of poor developed computer is regarded as a trial or a deepening for calculation method of member structure. Results of model test simulating actual designing entity in proportion to certain scale will be put into practice, and this is the main research method afterwards. Three-dimensional computerization really simulates designing entity and load conditions ，so this is an important method and also another casing research method. In the article，spiral casing structure simulated by three-dimensional computerization takes on high imitation ，utility，higher economic benefits，meanwhile it will resolve actual project problems.Characteristics of different material obtained from stress versus strain cure of cushion material are to analyze strain scopes at the respective stress ranges. Devising different test conditions affecting on stresses and strains are further analyzed. Characteristics of High pressure polyethylene plastic with lower froth are better than those of others in material tests，and it will be put into practice.Many factors control cushion thickness. By analyzing Laws of stresses and strains in the concrete under its different thicknesses，it is known that thickness affects extent of stresses and strains. So setting up four models with 0mm、30mm、40mm、50mm in thickness ，quantitative stress and deformation datum obtained from computerization models will resolve reinforcement problems from actual projects ，according as which cushion thickness will be reasonably selected. Changes in the scope of the cushion directly influence stresses and deformation in the its skirt ，specially more obvious in the changing part，so these can explain stresses sensitive to the scope of cushion in the weak part of the concrete. <WP=6>Elastic modulus of cushion is an important index and factor of spiral casing with cushion ，which directly impact on transferring ratio of inner water pressure from metal shell to stress in the concrete. In the computerization models with different thicknesses，all kinds of stress datum obtained by various numbers of elastic modulus can describe relation between these and elastic modulus，in the end，it will be used in the design and research of hydropower station.By three dimensional and part model, its stresses and deformations contract with results of the whole model，and relations between them are known, so provide bases for simplified calculation of feasibility and preliminary phrases. Plane FEM has capability of knowing precision degree of results by member structure method，and contracts with these of three dimensional whole model. Individual load affecting stresses and deformations is analyzed, when the individual load (inner water pressure) applied to the whole model, and so provides stress component for stress superposition under kinds of loads, meanwhile can indirectly analyze effect of another loads on stresses in the concrete.更多还原