2008 – Dams on Karst foundations risk assessment and remediation

Jeffrey A. Schaefer

Abstract: The U.S. Army Corps of Engineers (USACE) has numerous dams built on limestone foundations that are susceptible to solutioning (karst). Significant dam safety issues related to the karst foundation have developed in many of these projects. Screening risk assessments of the USACE portfolio of dams has shown that defects related to karst foundations is one of the largest contributors to our risk. To better evaluate this risk, a method to estimate the probability of failure from piping into karst foundations has been developed by team of experts from the University of New South Wales, URS, the US Bureau of Reclamation, the US Army Corps of Engineers. This paper summarizes the major failure modes associated with dams on karst foundations and the methodology developed to perform risk analysis. A summary of USACE case histories with karst foundation issues and recent projects to remediate the foundations are also included.

KEYWORDS: Dam, Seepage, Karst, Solution Feature, Risk

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