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充水保压蜗壳结构的受力和变形与保压间隙的闭合特性直接相关,进口结构连接形式对保压间隙的闭合特性存在潜在的影响.为此,采用有限元法模拟保压蜗壳施工到运行全过程.结果表明:保压间隙具有显著的提前闭合特性,提前闭合区从进口断面和45°断面外侧、270°断面内侧开始,随内水压力的增大逐渐扩展;达到保压水头时,未闭合区与最先闭合区空间上相对.伸缩节过缝时设置止推环或者引水钢管与蜗壳直接相连都能有效延迟保压间隙提前闭合的时机,对外围混凝土大部分截面的受力有利,座环承担的不平衡水推力和扭矩减小约50%.采用简化算法时,蜗壳外围混凝土大部分特征截面的合力明显偏小,且机墩上抬变形偏小30%~40%,可能导致设计不安全.
The force and deformation of the volute structure with water-filled pressure-retaining structure are directly related to the closing characteristics of the packing gap, and the connection structure of the inlet structure has a potential impact on the closing characteristics of the packing gap. For this reason, the finite element method The results show that the packing gap has a significant early closing characteristic. The advance closure zone extends from the entrance cross section and the outer side of the 45 ° cross section to the inner side of the 270 ° cross section, and gradually expands with the increase of the internal water pressure. When the head is closed, the space between the unclosed area and the first closed area is spatially opposite. When the telescopic joint is provided with a thrust ring or the water-conducting steel pipe is directly connected with the volute, it can effectively delay the timing of early closure of the packing gap. Of the force, the seat ring unbalanced water thrust and torque to reduce by about 50% .Using the simplified algorithm, most of the volute external characteristics of the concrete section of the cross section was significantly smaller, and the pier uplift deformation is small by 30% ~ 40%, may lead to unsafe design.