The principle and algorithm of composite element method (CEM) are briefly described. The major merits of the method are the preprocessing work load and difficulty can be reduced remarkably; and it can be coupled with finite element method (FEM) system very well. Then the physical model overloading test for Baozhusi Gravity Dam is illustrated. The overloading cases of numerical tests are carried out by three dimensional elasto-viscoplastic FEM and three dimensional elasto-viscoplastic CEM separately for the dam. The computational results are compared with the results from the model test. The comparison shows the displacements of the key points match closely. The whole displacements and stresses of two numerical methods also agree each other well. This research shows the validation of the CEM

and the main advantage of the algorithm: simple in preprocessing and accurate as FEM. Meanwhile

it is proved that CEM is an effective way to solve the deformation and destroy problems for the gravity dam on complicated rock base.