Sensitivity Analysis Of Arch Dam Stress Factors

As a secure and economy dam type, arch dam has became more and more applied in China’s water conservancy and hydropower construction. In recent years, with the start of the Western hydropower plant, a large number of high arch dam come to be built, such as:Xiao wan arch dam, Xiluodu arch dam, Jinpingerji arch dam. The water conservancy academia had a higher computational requirements of the arch dam safetyPerforming a structural stability analysis on a concrete arch dam involves several different tasks,or steps. One important task should include developing an awareness as too how different characteristics affect the behavior of the dam. Sensitivity analyses can play a critical role in understanding the effects these different structural and material parameters have on the structure.Mainly performing in the defect diagnosis at the arch dam runtime. Unfortunately,in many evaluations sensitivity studies are under utilized or overlooked all together.The results of the sensitivity analysis is often not used as a reference.The arch dam is a spatial shell structure which had variable thickness, mutative curvature and complex boundary conditions.So arch dam’s stress situation is very complicated. When the structural analysis of arch dam and it’s foundation began,we tend to consider many complex factors, and do a lot of field investigation and laboratory testing. The cost of traditional field investigations and laboratory testing would have significantly impacted the budget.To reduce project costs,we could use sensitivity analyses to help engineers gain a better understanding of which parameters had the greatest influence on the behavior of dam. Then, we could combine the traditional investigative and experimental method to carried out the Analysis.In this way, we can not only reduce the budget, but also improve work efficiency.In this paper, using finite element analysis software ANSYS10.0as a platform, adopting APDL parametric language to model an arch dam, and perform sensitivity analyzes by the grid sensitivity, load sensitivity and material sensitivity.In the grid sensitivity, example of stress concentration of holes was calculated, and the finite element’s solutions were compared with the exact solution.Then the meshing theory is extended to an arch dam, and obtained the arch dam’s grid sensitivity corresponding result, and use arch dam model2to verify the results. In the load sensitivity, using direct thermal-structural coupling method in ANSYS to do some analysis, and the analysis includes comparison of how the transient temperature loads and transient water pressure analysis impact on the dam’s stress situation and displacement situation. In the material sensitivity, analysis includes comparison of how dam and foundation’s material properties impact on the stress situation of arch dams.The analysis also includes comparison of how different dam foundation’s discrete part unit impact the calculation results. And the results were compared.The results show that:when the number of finite element mesh nodes of arch dam meet220per1000m3, you can get the stable results. Arch dam’s stress situation is more sensitive to the temperature load than the water pressure. The foundation material properties have greater impact on the stress of arch dam than dam’s concrete properties do.