Study On Dynamic Characteristics Of Foundation Structure Of Hydropower Station

Chinese terrain has a characteristic is that the west is higher than the east, the hydroelectric reserves and installed capacity in our country are first in the world. Water and electricity as a kind of renewable energy, in earth's energy increasingly tense situation, they have become a key support sustainable development and energy security. With the hydropower station scale, head hydropower, capacity is improved, generating units and workshop size increases, rigidity of structure reduce, and water-wheel generator will produce the vibration during operation of the working. In recent years, the research on the shaft vibration and the resulting combination of hydropower plant structural vibration machine pier research has become a common requirement and consensus. With some hydropower station as an example of practical engineering, establish a 3-d finite element calculation model, respectively from the model selection scope and boundary conditions to research the self-vibration characteristics, re-check the vibration and analysis the rigidity. Research contents and achievements mainly include the following aspects:1.About designing the workshop, Hydropower station design standard assumes the machine pier thick wall cylinder for calculating formula, re-check the vibration of the machine pier, including re-check the resonance and amplitude, the rules are simple. For large and medium-sized project in relatively complicated powerhouse structure, vibration problem is prominent, then use structural mechanics method will simplify the machine pier structure, ignored the differences between different parts of the stiffness and spatial effect. In summarizing the predecessors' experience and design results mature, adopt a 3-d finite element method, using the elastic supporting function of the surrounding rock to improve the concrete structure's stiffness and strength, while factory floor, the wind is overspread etc subsidiary structure of the coupling action should be taken into consideration.2.The dynamic computational of Hudson hydropower station include units excitation source and frequency analysis, structural natural vibration characteristic analysis and re-checking the resonance, calculating the amplitude, vibration displacement structure and stress computation, and using the dynamical method to further analysis, from the vibration displacement, velocity and acceleration to re-check of the vibration intensity. 3. About calculation model, comparing and analyzing different finite element model and the boundary constraint conditions. From simulating a single machine piers individual, then increasingly its upper part and the structure of the surrounding rock, until consider surrounding rock. From the results of the natural frequencies and mode of vibration shows that only consider a cylindrical part or mound and its adjacent upper machine or the lower structure, can't accurately reflect the actual vibration machine pier structure of state. And discussed the surrounding rock by rigid boundary supporting, elastic supporting of surrounding rock, then discusses the coupling effect of structure vibration characteristics influence.4. Because the difference between machine pier structural and boundary constraint conditions, the foundation structure is not completely axisymmetric, the structure of the stiffness each direction or the position exist certain differences. Calculation results show that the longitudinal stiffness is less than transverse stiffness; the vertical stiffness is large than machine pier level stiffness. In addition, a unit of a machine pier stress influence of unit machine pier is very small.