接触滑移对不同埋设方式蜗壳结构应力的影响分析

水电站厂房蜗壳结构中，蜗壳与外围混凝土之间的接触滑移客观存在。为研究接触滑移对蜗壳结构应力的影响，本文采用三维面面接触单元对不同埋设方式蜗壳结构进行了三维有限元计算。计算结果表明，考虑接触滑移后与共节点模型相比，垫层蜗壳外围混凝土孔周应力平均值可降低约30%以上，而钢蜗壳应力增加约27%；当摩擦系数由0.25增大到1.0时，蜗壳外围混凝土孔周应力平均值也增大30%左右；而考虑接触滑移与否对直埋蜗壳结构应力影响很小，差值不超过3%。因此在利用有限元求解蜗壳结构应力时，垫层蜗壳考虑接触作用将使计算结果更加合理，而对于直埋蜗壳和充水保压蜗壳，不考虑接触作用对结构应力的影响很小，共节点模型仍然可以在实际工程中采用。

Analysis of influences of contact slippage on stress of spiral case with different embedded manners

In the spiral case structure of hydropower station, the contact slippage between spiral case and surrounding concrete exists. In order to study the influences of contact slippage on the stress, the structures of spiral case with different embedded manners are solved by three-dimensional finite element method. In the calculation, the three-dimensional face-to-face contact element is used. Compared to the common node model, the average stress of the concrete in the spiral case with cushion layer reduces by more than 30% and the stress of the steel spiral case increases by nearly 27% when the contact is considered. The average stress of the concrete will increase by 30% when the friction coefficient between the interfaces in the spiral case with cushion layer increases from 0.25 to 1.0. However, whether to consider the contact has small effects on the stress of the complete bearing spiral case and the discrepancy of the results between the two models is no more than 3%. So it will be more accurate to consider the contact when to solve the structure of spiral case with cushion layer by finite element method. While to the complete bearing spiral case and the spiral case keeping constant internal pressure, the stress will be affected a little by the contact and the common node model still can be adopted in actual projects.