2024 PGS Workshop & 20th G.A. Leonards Lecture

April 12, 2024
Krannert Auditorium, Purdue University
West Lafayette, IN

Seismic Design Considerations for Tailings Storage Facilities

Video of Lecture | Lecture Slides | Paper: Performance-based Seismic assessment of slope systems (Bray/Macedo, 2023)

Professor Jonathan D. Bray

University of California, Berkeley

The seismic design of a tailings dam requires several levels of analysis informed by the site geology, seismic hazard, groundwater, surface water management, and material characterization, among other factors. Firstly, the potential for materials to lose significant shear strength due to earthquake ground shaking should be evaluated. Tailings are often composed of materials that have cyclic responses like that of sand, silt, and clay. Post-liquefaction shear strengths should be used to estimate the dynamic resistance of the dam. The seismic coefficient used in a pseudo static slope stability analysis must be compatible with the allowable amount of seismic slope displacement. The seismic coefficient can be selected to achieve an assessment consistent with the amount of seismic slope displacement that would have been calculated with a seismic slope displacement procedure based on a calibrated sliding block analysis. A robust seismic slope displacement procedure can capture the dynamic response characteristics of the slope with its fundamental period and the seismic demand with the 5%-damped spectral acceleration at the degraded period of the potential sliding mass and the moment magnitude of the governing earthquake. The uncertainty in the estimates of these parameters should be considered. With this approach, the engineer considers in a rational manner the amount of seismic displacement judged to be allowable and the seismic hazard at the site in the selection of the seismic coefficient. Given their criticality, a nonlinear effective stress-deformation analysis of the tailings dam should be performed. If properly calibrated, it can capture key mechanisms of deformation and provide important insights regarding the potential seismic performance of the tailings dam. A tailings dam breach analysis is required to assess the potential runout and its consequences.

Introduction by Vincent Drnevich, Purdue University

Jonathan Bray, Ph.D., P.E., NAE is the Faculty Chair in Earthquake Engineering Excellence at the University of California, Berkeley. Dr. Bray is a registered professional civil engineer and has served as a consultant on important engineering projects and peer review panels. He has authored more than 450 research publications on topics that include liquefaction and its effects on structures, seismic performance of dams, earthquake ground motions and site effects, and earthquake fault rupture propagation. He created and led the Geotechnical Extreme Events Reconnaissance (GEER) Association. Dr. Bray is a member of the U.S. National Academy of Engineering and has received several honors, including the Seed Medal, Terzaghi Award, Ishihara Lecture, Peck Award, Joyner Lecture, Middlebrooks Award, Huber Research Prize, Packard Foundation Fellowship, and NSF Presidential Young Investigator Award.

Presented in conjunction with the 20th Purdue Geotechnical Society Workshop - "Geotechnics of Dams"

Workshop Program | Event Photos

2024 PGS Student Committee

Support for the PGS Workshop and Leonards Lecture is provided by the following sponsors: