蜗壳结构是电站厂房的核心结构物,因此选择合理的保压值是确保大型水电站机组安全稳定运行的关键问题之一.针对云南某在建水电站充水保压蜗壳的不同保压值,对保压蜗壳结构进行了应力状态和变形情况分析.结果表明:保压值越大对蜗壳外围混凝土的受力越有利,但保压值过高,导致蜗壳与混凝土之间的脱离间隙过大,在运行时蜗壳和混凝土两者联合承载的效率太低,不仅混凝土的承载作用没有得到良好发挥,而且结构整体刚度降低,易产生共振,对机组稳定性不利.通过比较,该机组设计保压值偏高,选取1.6 MPa保压值时,混凝土的应力较合理,结构也能满足刚度要求.%Spiral case is the core structure of powerhouse, therefore, choosing the right preloading pressure is critical to guarantee the safe and stable operation of station. In this paper, we use different preloading pressure for mechanical characteristics study of a large hydropower project with preloading water-filled spiral case. The numerical results shows that with the increase of the value of preloading pressure the stress states of surrounding concrete get better. But the too high preloading pressure, lead to the gap between the spiral case and surrounding concrete is too large, structure stiffness has been reduced, which may result in structure resonate. When the preloading pressure is 1. 6 Mpa, the stress state of surrounding concrete is reasonable and structure is unease to resonate. The numerical achievements are helpful to improve the design and construction of surrounding concrete of preloading water-filled spiral case structure.
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