Three-dimensional Non-linear Finite Element Analyses Of Stress-Strain And Stability Of Baise 3B Dam Block

The stress ,strain and sliding stability are important contents for the design of gravity dam. 3B dam block of Baise RCC gravity dam has three primary characteristics: 1.There are many spatially intersected holes in the 3B dam block, such as drainage gallery, elevator well etc. so that the rigidity of the dam is remarkably weakened; 2.The dam base is located on steep slope; 3. The dam foundation is consisted of a series of soft and hard rock with a down-stream inclination of 50～70°and elastic modulas ratio reaches as high as 20 times, in addition , the foundation rock mass contains 4 groups of joints and fissures. As a result, the stress & strain and the stability of 3B block is an essential control factor to the project's success. In this paper, the three-dimensional non-linear elasto- plastic model is applied to analyze the stress , strain of dam and the stability of 3B block. The main works of this paper are as follows:1.Three-dimensional non-liner finite element method is adopted to study the displacement and stress distribution along the river and across the river under several static working conditions, then, the results are compared with that under assumed uniform foundation and that of other same type dams. The research results show that the down stream displacement of Baise RCC dam(0.397‰ of its height) is relatively large in the same type dams. The displacement of uniform foundation is much less than that of the practical non-uniform foundation. The effect of the foundation treatment measure is appraised by analysis of stress state on dam heel. In addition, the strain and stress of internal holes of 3B block are provided for future design of reinforcement. At last, the overloading safety factor law and synthesis safety factor law are applied to analyze the stability of dam base, to model the base rock's failure process, and to analyze its failure mechanism, failure mode and failure path. 2. Mode decomposition response spectrum method is adopted to study the typical periods and typical modes of 3B block. The dynamic stress and dynamic displacement are evaluated under seismic condition. Then the synthesis safety factor law is applied to determined the dynamic safety factor and its possible sliding paths. The result shows that the least dynamic safety factor Ks of 3B block is 2.2, satisfying the requirement of state specification.3.A program based on Scripter Language of Surfer8.0 is designed to facilitate the plot of topographical plots. With this program, contour maps can be generated automatically, thus greatly increases the efficiency.