Cushion spiral case structure is commonly used in the powerhouses of large-scale hydropower stations. In this study, the three-dimensional finite element method is used to analyze the mechanical characteristics of cushion spiral case structure of a hydropower station. The stress state of the steel spiral case, as well as the cracking range and stress distribution of the reinforced concrete during normal operation under ultimate limit state and serviceable limit state are analyzed and compared. The analysis results have verified the rationality of the selection of spiral case type and provided a reference for the reinforcement design of surrounding concrete of the spiral case.

hydropower station, cushion spiral case, finite element method, structural design

垫层蜗壳是大型水电站厂房蜗壳的常用结构型式。运用三维有限元分析方法对某水电站垫层蜗壳结构的受力特性进行研究，分析比较了承载能力极限状态与正常使用极限状态下正常运行时钢蜗壳的应力状态、钢筋混凝土的开裂范围与应力分布规律。分析成果验证了蜗壳型式选取的合理性，并为蜗壳外包混凝土配筋设计提供了参考。

水电站, 垫层蜗壳, 有限元计算, 结构设计