| Gravity dam is the main dam of high dam construction in China, it occupies relative large proportion of large and medium-sized built dam in Water Resources and Hydropower Engineering from beginning to end. Gravity dam mainly relies on its own gravity to maintain the stability, with large volume, good stability, but for various reasons, it still may be breaked. If the dam breaks, it will not only destroy the works, but also cause devastating disasters to the economic construction of the downstream areas and people's lives and property.As a result, analyzing stress-strain of Gravity dam has been a concerned problem in gravity dam design and engineering.The sediment discharge of QingYu reservoir dam as this study, it has many spatially intersected holes in the spillway dam block, such as drainage gallery, elevator well etc, forms complex spatial stress field, so that the rigidity of the dam is remarkably weakened. As a result, the stress - strain of spillway block is an essential control factor to the project's success. In this paper, the three-dimensional non-linear elastc-plastic model is applied to analyze the stree-strain of dam of spillway block. The main works of this paper are as follows:1,Strain Analysis: In both cases that without considering dam weight and consideration, study water pressure and sediment pressure deformation effects to the dam. The results showed that the dam to the downstream deflection in the both cases, but in case of without considering dam weight horizontal displacement is larger than in case of considering dam weight , downward settlement situation is much smaller than in case of considering dam weight. In both cases, the holes in the dam are deflection to the downstream coordinated with the dam, the presence of spillway shows little effect to deflection gallery.2,Stress Analysis: Through splitting each hole along the axis holes, the stress distribution obtained as follows:①As the existence of holes inside the dam, the stress around the hole appeared the stress concentration;②Foundation grouting gallery and dam drainage gallery have the same stress changes, that is both in the roof of the gallery and the floor occur tensile stress, the tensile stress value is small, the stress is diagonal symmetric distribution in gallery ;③The maximum tensile stress is in the middle of the bottom and the roof of a spillway , the maximum compressive stress is in four corners of a spillway;④The maximum of various stress locate the bottom of the section of gate shaft;⑤Since the existence of spillway, the concentration stress value in gallery changes suddenly than the other adjacent dam;⑥Circumferential tensile stress value around the holes is small, if certain requirements by the stress of reinforcement design are to meet the stress of dam safety requirements.3,Under the condition of empty library, a dam does not appear plastic stress or plastic strain, it does not exist a plastic region. Under the condition of normal water level and design water level, the dam plastic region situated dam heel 0.5m of upstream side of bottom of the dam, plastic region is smaller.4,Results compare: Comparing the results of three-dimensional nonlinear finite element method with the conventional method, we can see that the finite element method concentration stress is greater than conventional method, when designing reinforcement at the stress concentration of holes, finite element calculations are appropriate.
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