中文摘要：

机组运行时蜗壳座环在不平衡水推力作用下承受较大的水平剪力，该剪力值过大将会给蜗壳结构的稳定带来安全隐患．考虑钢衬与软垫层、混凝土的摩擦接触，建立了垫层蜗壳的三维有限元模型，详细研究了垫层子午包角、平面包角、变形模量厚度比和围岩约束对座环剪力的影响．结果表明：垫层子午包角向下延伸不利于座环抗剪；垫层平面包角变化改变了钢蜗壳外围结构的刚度分布，对座环剪力具有显著影响；垫层变形模量厚度比的变化不仅改变了座环各向剪力的数值及其承担的沿厂房横向不平衡水推力的比例，还改变了座环剪力的空间分布规律；在其他条件不变的情况下，围岩约束的改变对座环剪力没有明显影响．

英文摘要：

The stay rings of spiral case bear a considerable horizontal shear under unbalanced hydraulic thrust, and an excessive shear will endanger the stability and safety of the whole spiral case structure. A 3-D FE model for spiral case is established by taking into account the contact slippage between the steel liner and surrounding concrete and cushion layer. A detailed study on the effect of the radial wrap angle, the flat wrap angle, the ratio of deformation modulus to thickness of cushion layer and the constraint of surrounding rock on the shear property of stay rings is conducted. The experimental results indicate that the downward extension of the soft cushion layer radial wrap angle will increase the shear on stay rings. The alteration of flat wrap angle changes the rigidity distribution of structures surrounding steel spiral case, which has a remarkable influence on the shear of stay rings. The alteration of the ratio of deformation modulus to thickness of cushion layer changes the shear value between stay rings and concrete, the share proportion of transverse unbalanced hydraulic thrust by stay rings, and the spatial distribution of shear on stay rings. The constraints of surrounding rock have no influence on the shear of stay rings with other conditions unchanged.