Design of Gravity Dams on Rock Foundations. Sliding Stability Assessment by Limit Equilibrium and Selection of Shear Strength Parameters.

摘要

The limit-equilibrium method applies the factor of safety directly to the least known parameters of sliding stability assessments; that is, the shear strength of the founding material. Because shear strength forms an important part of any sliding stability assessment, this report also offers information on methods for the selection of design shear strengths for structures founded on rock mass. Shear strengths selected for design must consider certain prerequisites. Prerequisites briefly discussed include: field investigations, loading conditions, shear tests, material stress-strain characteristics, failure criteria, linear interpretation of nonlinear failure criteria, and the level of confidence that should be placed in the selected design strengths. Modes of potential failure for a structure founded on a rock mass may be through intact rock and/or along clean or filled discontinuous rock. Methods which form the bases of shear strength selection are dependent upon modes of potential failure. Currently acceptable methods, including shear tests, empirical concepts, and rational approaches, are discussed. Particular emphasis is given to alternative approaches in selecting design shear strength parameters c and 0 as the approaches relate to the level of confidence that must be placed in the design strengths.