A Study Of Critical Global Energy Error Limit On Gravity Dam Adaptive FEM Stress Analysis

Recently, the conception of Critical Global Energy Error Limit (CGEEL) has been frequently cited in FEM analysis for hydro-structures, particularly for gravity and arch dams. In association with the conception of CGEEL, researchers are trying to solve stress distortion around dam heel and the rule of mesh generating in FEM analysis.In this paper, the review of CGEEL of adaptive FEM analysis for gravity dam has been made. Focusing on the potential problems of current CGEEL, the content has been clarified in this study which is about to further investigate CGEEL using h-type adaptive FEM and associating with powerful FEM tool, ANSYS.First, for the purpose of oneness for conclusion, the validations for published CGEEL cases have been done by using uniform calculating method. The results show:(1) Validation for Yang's case. There is a global energy error limit which makes stress around area outside 0.02B dam heel stable.(2) Validation for Li's gravity dam case. The value making stress around area outside 0.03B/0.024H stable is some 2.However, the above mentioned conclusion could be considered as general one due to the sole dam geometry. In this study, the investigations have been explored by focusing on complex dam conditions with different dam height, upstream slope and downstream slope. The results have been obtained as following(1) Results for various height and downstream slope: CGEEL would be chose less for the situation of increasing downstream slope for same dam height. The value should be less too for increasing dam height at same slope.(2) Results for various height and upstream slope: CGEEL has little change for the situation of increasing upstream slope at same dam height. The value should be less for increasing height at same upstream slope.The below conclusions have been made according to above manifold investigations(1) There exists CGEEL during adaptive FEM stress analysis for gravity dam.(2) Although CGEEL is slightly oscillating for different dam geometries, the amplitude of oscillation is quite small so that the conclusion that 2 could be considered as general CGEEL can be made. It is believed that the obtained results in this study will be helpful for dam FEM analysis and for making uniform rule for gravity dam FEM analysis.