【作者】 魏燕；

【导师】 李守义；

【作者基本信息】 西安理工大学 ， 水工结构， 2008， 硕士

【摘要】 随着垫层蜗壳被越来越多应用于国内外各个大中型水电站中,设有垫层的蜗壳结构的动力特性越来越被人们所重视。在设垫层的蜗壳结构中,由于钢板与混凝土间有软垫层的存在,使混凝土对钢蜗壳的约束作用降低,可能会导致对机组运行稳定性的不利影响,这是选择垫层蜗壳的重大疑问之一,过去国内虽然对垫层蜗壳做过大量的研究,但缺少对其动力特性的分析。因此对设垫层的蜗壳结构的动力特性研究成为水电工程中迫切需要研究解决的关键课题。本文利用二维有限元计算分析了特定的蜗壳结构在外力激励下的动力响应问题,以及在没有外力激励下蜗壳结构本身固有的动力特性等问题。另外,在对设垫层的蜗壳结构自振特性分析的基础上,还对机组振源进行分析,并进行蜗壳结构的共振校核。以某工程为例改变垫层情况和蜗壳结构形式分别对设垫层的蜗壳结构的自振特性进行计算分析。选用不同垫层的材料的与采用不同垫层铺设的范围的计算结果表明,蜗壳结构的自振频率会随着垫层材料的弹性模量的增大而变大,但当垫层的材料的弹性模量大于3.5MPa时,垫层材料的改变对蜗壳结构的第2到6阶的自振频率影响不大。蜗壳结构在铺设相同垫层材料而用不同垫层铺设范围的情况下,蜗壳结构的自振频率会随着垫层的铺设范围的增大而减小;改变钢蜗壳外围混凝土的浇筑厚度与钢蜗壳直径的计算结果表明,加厚了钢蜗壳外围混凝土的厚度,增大了蜗壳结构的刚度,使得蜗壳结构自振频率的会随着钢蜗壳外围混凝土的浇筑厚度的加厚而变大,而当钢蜗壳外都采用同样的混凝土浇厚度时,蜗壳结构的自振频率会随着钢蜗壳直径的变小而增大。更多还原

【Abstract】 Along with spiral case using cushion layer be more and more been applied in each domestic and international big and medium-sized hydroelectric station, motive characteristic of structure of spiral case using cushion layer drive more and more people regard, because of steel plate and concrete have a soft mat layer to save greatly in structure of spiral case using cushion layer ,which make function of restriction of the concrete steel shell a to lower, may cause the disadvantageous influence when unit is circulating. That is one of the important questions which choose a spiral case using cushion layer. In the past although the domestic once did a great deal of research about structure of spiral case using cushion layer, scarcity analysis of motive characteristic, therefore study about motive characteristic of structure of spiral case using cushion layer need to solve urgently in hydraulic engineering.Architectural motion differential equation the main body of a book is deduced out taking Hamilton (Hamilton) principle as the basis. Solved particular certain structure to encourage in the outside power ,the motive of the structure responds to a problem .And under not having the outside force excitation, the structure proper and dynamical characteristic problem, study the vibration source in hydropower plant, and resonance checking is given to the spiral case using cushion layBesides, the main body of a book try to imitate by numerical value , take some’s projects as the example secretly scheming against , change bed course condition and the snail shell structure form respectively , carry out analysis on the architectural snail shell self vibrate characteristic property setting up a bed course. The result when selecting and using the material being unlike a bed course’s and adopt the range that the be unlike bed course lays, secretly scheming against is indicated , is enhance but is changed into the architectural snail shell self vibrate frequency meeting with putting in tier of the material elasticity moduli’s big, under lay cospecific bed course material but lay range’s with different bed course situation, architectural snail shell self vibrate frequency will be with the bed course laying range enhancing but diminishes; But in changing the snail shell structure form, the result respectively, changing the steel snail shell outer-ring concrete’s when concrete thickness and the steel snail shell diameter, secretly scheming against indicates, concrete that snail shell structure will be from shaking frequency’s with steel snail shell outer-ring concrete thickness’s be thickened by but change big, architectural snail shell self vibrate frequency will be small with steel snail shell diameter unexpected turn of events but enhances when adopt the same concrete to irrigate thickness as if it be the steel snail shell outside.更多还原