Alternative Method to Model Dam Concrete-Rock Foundation Interface Shear Strength

This paper discusses the application of the Barton-Choubey method in gravity dam analysis of sliding stability on a concrete-bedrock foundation interface. It discusses the non-linearity of the Barton-Choubey shear strength envelope as compared to the linear strength envelope using the conventional Mohr-Coulomb method. It discusses field and laboratory measurements of key variables for use in the governing equation (Eq 1). After discussing the method and measurement of input data, it shows how this method has been applied at selected hydroelectric gravity dams in the portfolio of Erie Boulevard Hydropower, L.P. (Erie). Lastly, some recommendations for use and suggested further research are presented.

This method has been proposed in the past for use in analysis of concrete gravity dams, for example, “The Assessment of Sliding Resistance Beneath Concrete Structures” by Donnelly, R.C. and Rigbey, S.J. (2007), however, the current authors have not seen broad industry adoption, possibly due to a lack of common regulatory acceptance. It is hoped that this paper will help to rekindle consideration of this method in the dam safety community, with specific usefulness for supplemental stability analyses of existing post-tension anchor assessment under newly increased extreme flood loading and possibly assessing deficient concrete dam stability in FERC Comprehensive assessments.