混流式水轮机发电机组钢衬蜗壳有不同埋设方式，三峡水轮发电机组钢衬蜗壳是目前世界上混流式水轮机最大的蜗壳，左岸电站全部为保压方案。针对右岸水电站厂房钢衬蜗壳2种埋设方案，建立三维有限元模型,研究蜗壳保压方案和垫层方案的固有振动特性和地震响应，采用振型叠加反应谱法计算地震动力响应，分析不同蜗壳埋设方案对结构的自振特性及地震响应的影响。分析结果表明：就抗地震作用而言，2种方案都是可取的，垫层方案略优于保压方案。

There are various embedment options for the steel-lined spiral case of Francis turbine unit. Only constant-pressure option was adopted in the steel-lined spiral case in the  left bank hydropower plant of Three Gorges Project. To study the earthquake resistance of two embedment options for spiral case in the right bank hydropower plant, this paper presents a 3D finite element model to study the natural frequencies and seismic responses of steel-lined spiral case embedded under constant-pressure and embedded with supporting lining layer. Dynamic response of earthquake is calculated by the superposition of vibration modes. The analysis results indicate that different embedment options have little impact on structural natural frequency and seismic response. Both embedment options are feasible in earthquake resistance design, with the latter slightly better than the former.