Unified criterion for calculating the safety factor of slope stability for earth dams

Conclusions

• 1. As the evaluation criterion of slope stability one should take the concept of degree of use of the bearing capacity of the surface (section) with respect to shear stresses, i.e., should consider that the factor of safety against sliding is equal to the ratio of the areas of the diagrams of the limit (determined with respect to a generalized angle of shear) and actual shear stresses (under actual normal stresses, Eq. (3)). The proposed criterion can be used for any slip surfaces and types of forces. In this case ksaf can be determined not only on the basis of Mohr's theory but also on the basis of any mechanical theory using the strength condition due to Mises-Schleicher-Botkin, etc.

• 2. In conformity with the proposed determination of k_saf it is recommended to calculate the stress-strain state of a dam from all acting factors by computer with further determination of k_saf on any slip surface. The solutions obtained within the framework of the given soil model will be exact and unique.

• 3. The proposed method of determining ksaf in the absence of external additional forces and the assumption that the normal stresses on the slip surface are determined from the equilibrium condition of the fragment under the actual forces (without consideration of the interaction forces) corresponds mainly to the approximate cylindrical-surface methods, using as k_saf the ratio of the moments of the restraining and shearing forces (the 1941 VNIIG, Bishop, and other methods) from the broken-surface methods (the Maslov-Berer method). The certain discrepancies between the present and the proposed method are explained by the assumptions made by the authors to simplify the relations.

• 4. Given field data on the stress-strain state of the dam body, the proposed method permits checking the quantitative evaluation of the degree of stability in the operating period.