DYNAMIC CENTRIFUGE TESTS OF CONCRETE GRAVITY DAM

This paper reports on dynamic centrifuge tests results, and their numerical simulation. In the test reported in this paper, a 60 cm-high model of a concrete gravity dam was first subjected to a centrifugal field of 30G and then excited through harmonic stream accelerations with increasing amplitude. Hence, through the eventual crack formation and propagation, failure (or limit state) of the dam was modeled. Numerical analyses for prediction and simulation of the test results with a special purpose nonlinear fracture mechanics finite element code are also reported. Limit states assessment of earthquake-resistance must be performed in order to provide an effective justification for major dam maintenance or rehabilitation. As most damage in concrete dams manifest themselves through cracking. Fracture Mechanics is used to assess those limit states. With this background, the authors are investigating methods to assess the safety of concrete dams during earthquakes and are developing codes for 3D dynamic non-linear analysis with discrete crack models. Hence, whereas the tests did not model one dam in particular, their intent was to assess the computational tools capability in properly simulating not only its nonlinear response, but also its failure. It should be noted that the upstream side of the model was impounded to simulate the reservoir presence. Finally, monitoring was performed through extensive instrumentation, which included two or more accelerometers and strain gauges in the foundation and throughout the dam body