3D-FEM Analysis On The Spiral Case Structure Of Xi-Longchi Pumped-Storage Hydropower Station

Recently, more and more preloading filling spiral case structures are in application as general hydropower generator unit and pumped-storage hydropower generator unit tend towards large capability and high head. Preloading filling spiral case structure, which is composed of steel scaleboard and reinforced concrete, is a kind of complex material structure, a kind of special unsymmetrical structure. The structure bears not only hydrostatic pressure and hydrodynamic pressure that vary in a range but also the weight of hydropower generator unit and the variable loads exiting in the course of examining and repairing. How to carry out analysis, especially 3-D nonlinear analysis, on such a special structure is still not well solved. The maximum hydrodynamic water head of Xi-Longchi pumped hydropower station is 1015m, the spiral case structure works in such a high water head, its stress status is concerned by the engineers. In the paper, 3D-FEM linear and nonlinear analyses were made on the spiral casing structure in Xi-Longchi pumped-storage hydropower station by ANSYS.In linear analysis, the stress status in spiral case structure was analyzed in consideration of different KI values. The results show that the control stress is concrete circumferential stress and KI value has an important effect on the concrete stress status. A suitable KI value is suggested based on the stress analysis and operation conditions. And the scheme of reinforcing steel in surrounding concrete is proposed according to the linear calculation results.In nonlinear analysis, a 3D-FEM nonlinear model is building on the basic of correctly modeling steel spiral case, concrete, steel bar and the connection between them. A nonlinear calculation is made on the spiral case structure in Xi-Longchi pumped-storage hydropower station. The development and the distribution of the cracks in the surrounding concrete and the stress status of the structure after cracking are analyzed, which obtains good results. The conclusions supply reference to researching the destruction as well as design of spiral case structure.