An approach to the estimation of safety of concrete dams on rock foundations is discussed from the viewpoint of strength and bearing capacity of the latter. Design and experimental aspects of the problem in question are considered.
This report discusses the approach being employed at the B.E.Vedeneev VNIIG for estimating safety of concrete dams on rock foundations from the viewpoint of strength and bearing capacity of the latter.
In accordance with the Design Codes the said estimation should be performed by carrying out two kinds of calculations: the calculations of general stability (for all structures) and those of local strength of the foundation (for Class I magnitude structures only).
The use of conventional methods is necessary and sufficient for calculating the general stability of a structure provided that the design shear force does not exceed the ultimate shear strength (with safety factors taken into account). This condition is to be Checked for all potentially hazardous design shear surfaces (both flat and broken ones). At that, two kinds of shear are possible for the broken surfaces: the longitudinal shear (along the arrises) and the lateral shear (across the arrises).
When defining ultimate shear forces it is recommended to take into account the shear strength of the downstream toe (undisturbed rock or backfill). The value of this strength depends on the relationship between the deformation modulus of the toe material and that of the foundation and varies from 0.7 Ep to Er, where Ep and Er are the passive Coulomb pressure and the pressure at rest, respectively.
The local strength of the foundation is calculated (1) to decide on the necessity of measures preventing possible damage to the watertight elements, (2) to be taken into account when elaborating measures meant to increase the strength and stability of the structure and (3) to check whether the ultimate value of the same is reached when estimating the stress-strain state of the structure and foundation.
L'approche à l'evaluation de la securite des barrages en beton sur fondations rocheuses est discutee. On examine les aspects analytiques et experimentaux du probleme.
Es wird einen Ansatz zur Sicherheitsbewertung von Betonstaumauern auf Felsuntergruenden unter Gesichtspunkt der Tragfahigkeit und Festigkeit der letzteren beschrieben. Es wird berechnete und experimentelle Aspekte dieses Problems betrachtet.
