 
America's Most Powerful Centrifuge Testing Dam Safety at CU-Boulder
The scale-model, two-ton dam in the payload box was constructed with a small sinkhole similar to depressions occasionally found in earthen dams around the world. By "flying" the tiny dam at blurring speeds using a 900 horsepower motor, researchers can determine how sinkholes propagate to the surface of full-sized earthen dams under stress, says civil engineering Professor Hon-Yim Ko. The secret is in the swing of the centrifuge, which is similar to filling a bucket of water and swinging it in circles without losing a drop. Ko is testing the dam for the U.S. Bureau of Reclamation.
Chairman of the civil, environmental, and architectural engineering department, Ko has conducted a wide variety of experiments in the machine with colleagues and students over the years, ranging from dam safety and the interactions of giant anchors with the sea floor to the behavior of lunar-like soil overlying tubular or spherical structures. In addition to the 400 g-ton centrifuge - which can simulate the behavior of structures as large as a football stadium - the department also has a smaller 10 g-ton centrifuge. The centrifuges are constructed so water can be added to miniature dams in flight to simulate the erosion effects of earthen dam "overtopping" and determine failure points, Ko says. Researchers use "shake tables" that move laterally inside the payload boxes to simulate soil behavior under earthquake conditions. "You rarely see dams being torn down they either break or are declared unsafe," Ko says. "The safety of existing dams has become an important issue, and our machines are providing a viable way to study it." While computer simulations have become a popular technology of predicting the outcomes of geophysical events, physical-modeling studies like those performed in centrifuges and wind tunnels are invaluable, Ko says. "At times, computer simulations only tell you what you already think, and do what you want them to do. On the other hand, a structure will tell you what it wants to do. That is why these physical experiments are irreplaceable."  Engineering Home |
In the basement of CU-Boulder's College of Engineering and Applied Science, a monstrous centrifuge sporting an 80,000-pound swinging arm and a box to tote hefty payloads whirls a miniature earthen dam at 200 miles per hour.
Capable of spinning two tons of material at 200 times gravity, the 400 g-ton machine - among the most powerful centrifuges in the Western world - uses the force of gravity to simulate the behavior of full-sized earthen and concrete structures under stress.