Abstract: The calculation of shallow and deep slide-resistant stability of dam involving foundation surface and weak structural planes is very complex. On the basis of conventional method for double failure faces, the principle of equal safety coefficient was adopted to derive the nonlinear equations for stability analysis, and an iterative solution was proposed based on the characteristics of these equations. The assumptions in this solution are in line with the general requirements of current specifications and industry designs. Calculation example of a gravity dam verified the feasibility and accuracy of this solution.

Key words: foundation surface, weak structural plane, slide-resistant stability, multiple failure faces, safety coefficient