Abstract: Stability analysis and failure mechanism of earth dam are of important engineering significance. By using centrifugal force to simulate gravity, centrifuge model test has effectively solved the problem of stress equality in model test. As a result, centrifuge model test has been an important means to investigate the deformation and failure process of earth dam. This article focuses on the deformation and failure behavior of earth dams under piping condition. Centrifuge model tests on failure of earth dam with weak layer were conducted based on improving the previous equipment. Test results show that the process of the failure of earth dam with weak layer is as follows: a piping channel forms gradually at first, and in subsequence, the lower dam is washed away gradually, and upper dam collapses in the meantime, and the whole dam breaks in the end. The breakthrough of the piping channel is an important influential factor, and even could be the prerequisite of dam failure.

Key words: weak layer, earth dam, centrifuge modeling, dam failure, deformation