Design standards for dams are effective for earthquakes: study
The collaboration’s computer simulations, validated by experimental tests run by the ERDC, show that the dam filters that meet today’s existing standards for reservoirs are effective for protection.
Furthermore, the computer simulations can be used to assess filter success or failure under different soil or loading conditions and can lead to meaningful estimates of the timing and nature of major dam problems caused by internal erosion from the core through the filter materials.
“The Laboratory’s computer simulations and the physical experiments performed by the ERDC compared very favorably,” Glascoe stated.
Mary Ellen Hynes, the senior engineering adviser of the DHS Science and Technology Directorate’s infrastructure protection and resilience programs, said the team’s effort represents a “superb body of research.”
“For decades, we have wanted to be able to numerically model the transport of particles through filter zones to test against our empirical data. This collaboration has given us the information we needed,” Hynes added.
One of the team’s major findings, according to Hall, is the development of initial computational tools to predict how the interface between a dam’s concrete section and embankment sections with the sections’ filters will behave during earthquakes and other severe events.
ERDC geotechnical and structural engineers ran experiments at their facility’s Centrifuge Research Center, the world’s most powerful centrifuge, using a one-foot-high model dam that was subjected to thirty times the force of gravity.
“We tried to scale the structure, as if we had a 30-foot dam,” Hall said.
In a follow-on experiment, they utilized larger glass beads, at about 1,500 microns, to simulate the soil filters, and smaller beads at 350 and 50 microns to serve as the impervious clay core materials, with normal water flows and high pressure water flows.
“The whole purpose of the ERDC’s work was for us to conduct the correct experiments to generate data that could be used to validate the numerical tools or computer simulations of LLNL,” Hall said.
Glascoe called the three-year joint project one of the best collaborations he’s ever been involved in.
“It leveraged the inherent strengths of both laboratories: the ERDC being the engineering lab with the experimental expertise and LLNL bringing the ability to develop and apply high-fidelity numerical simulations,” he said.
“We wouldn’t have been able to solve this problem by ourselves. Without the ERDC’s experimental validation of our models we could have easily drifted into a theoretical and numerical ‘sand box.’ The ERDC engineers helped to ground us in the reality and needs of the dam engineering community,” Glascoe added.
For the future, the Lab engineer said that the team would like to use computer simulations to make soil filters more effective and better understand the timing and nature of possible full-scale dam failures caused by erosion.
— Read more in S. Ezzedine et al., Modeling of Long-Term Fate of Mobilized Fines Due to Dam-Embankment Interfacial Dislocations (LLNL-PROC-491853, 3 August 2011); and L. Glascoe et al., Evolution of an interfacial crack on the concrete-embankment boundary (LLNL-TR-645956, 11 November 2013)
