Assessment On RCC Dam Safety Impact Of Horizontal Weak Layer

As the maturity of the design and construction of Roller compacted concrete gravity dam, it has showing the trend to high dam. At present, the Longtan hydropower dam in construction now is the highest roller compacted concrete gravity dam in the world. Roller compacted concrete dam is different from ordinary cast-in-place concrete dam because it is formed by roller compaction on concrete layer. The safety of dam will be impaired if the shear strength of construction interface is poor. So we need to calculate the anti-sliding stability in foundation surface and in RCC layer.Because of the large rolling deck and continuous construction in high temperature and wet season during the Longtan hydropower dam construction process, it is possible for partial area with the weak layer existing in the individual monolith. The main task of the study in this paper is analyzing and estimating the safety of RCC dam with the weak layer.A 2D finite element model is established to analyze the impact of weak layer from the angle of anti-sliding stability and study criteria for evaluating stability of dam. Nine different random weak layers considered in the condition of the position are unknown. The application of failure criterion of slope is feasible. Some major anti-sliding stability calculation methods have been discussed such as the rigid body limit equilibrium methods, FEM method based on partial coefficient, the material strength reserve method and so on. These methods are used to calculate anti-sliding stability safety factor. In this paper, the method has been put forward in which strength reduction non-linearity FEM is used to judge the dam stability and compared to other methods. Moreover, the reliability has been proved to corresponding to the safety factor.In dynamic analysis, the fluid-structure interaction equation is established on the basis of the impact of water vibration. Viscous-spring boundary and generalized Newmark- β method are adopted to obtain seismic response. Safety factor and reliability have been calculated and compared to the results in static analysis on the basis of elastic analysis.At last, a summary of the final results is supplied in this paper. The assessment on the RCC dam safety impact with the weak layer is made after the most unfavorable work condition is found. Some advices and deficiencies have been given to the later research.