直埋式蜗壳三维非线性有限元静力计算

直埋式蜗壳具有明显的优势，但在我国迄今尚无实际的工程应用。三峡右岸电站15#机组蜗壳拟采用直埋式方案，蜗壳结构的可靠性、机组运行的稳定性等都需得到数值计算和模型试验的验证。为此，本文运用钢筋混凝土弹塑性断裂损伤模型对该蜗壳结构进行了三维非线性有限元分析，得到了钢材的应力、混凝土损伤范围、混凝土裂缝宽度和结构位移。计算结果表明，直埋方案从强度上可以保证蜗壳结构的安全，若能采用适当的工程措施，将混凝土裂缝宽度限制在规范限定的要求以内，那么三峡右岸电站15#机组蜗壳采用直埋方案是完全可行的。

Three-dimensional nonlinear finite element static calculation of complete bearing spiral case

Complete bearing spiral case is a kind of preponderant spiral case,which has not been applied to large power stations in our country so far.If this embedment method is applied to No.15 turbine unit in Three Gorges Hydropower Station,the reliability of spiral case structure and the security of units under working condition must be verified by both numerical calculation and model test.Therefore,a three-dimensional nonlinear finite element analysis has been carried out by using a damaged plasticity model for concrete.Accordingly,the stress distribution of spiral case and rebar,the range of damages in surrounding concrete,the width of concrete cracks,and the displacement of structure are obtained.The result shows that the embedment method ensures the structure's safety in strength.The application of this embedment method to No.15 turbine unit of Three Gorges Hydropower Station is feasible if some appropriate engineering measures are adopted for limiting the width of concrete cracks satistying the(code's) requirement.