Authors: D.D. Curtis, K. K.Y. Lum
Canadian Dam Association Conference, Winnipeg, September 2008
Abstract
There are situations in the assessment of concrete arch and gravity dams where the shear strength of the shear keys is important. One example is a gravity dam in a relatively narrow valley subjected to intense seismic loading. For this case, the dam may be computed to be unstable if horizontal loads can not be transferred laterally to the abutments. The lateral transfer of loads to the abutment relies on the strength of the shear keys. In a recent analysis of Ruskin Dam, located in British Columbia, assessment of the strength of the shear keys was undertaken when a non-linear finite element model found that significant forces were being transferred laterally to the abutments during an earthquake.
In this paper, the shear strength measurements obtained from the literature are reviewed and compared to shear strength measurements obtained by BC Hydro from cores taken from Ruskin Dam. Also, a relatively simple ultimate shear strength equation is developed using the Mohr-Coulomb failure criteria.
It was found that shear key strength reported in the literature compares well to that measured at Ruskin Dam (after adjustment for compressive strength differences). In addition, the cohesive strength obtained using the Griffith failure criteria also compared very well to both sets of measurements. The results given in this paper may be useful for the evaluation of existing and new dams where 3D behaviour is important.
