Arch dams transmit to the foundation important loads; particularly, they have a high magnitude with one determinant horizontal component. To define the optimum foundation level of these type of structures on a rock mass, it is necessary to know the orders of magnitude of the safety factors incorporating the main factors that determine the ground response: type of rock, quality of the rock media, uniaxial compression strength of the rock matrix, load inclination, depth of the foundation, inclination of the surface of contact, etc. A real case is presented showing the influence of the variations of the different parameters involved in the obtained safety factors, for the bearing capacity of the rock mass. The original Hoek & Brown (1980) failure criterion has been used together with the Serrano & Olalla (1994) methodology to calculate the ultimate bearing capacity.
In all typologies of dams it is necessary to consider the dam-foundation interaction, in order to evaluate its resistance and deformability. In double curvature arch dam this is particularly important.
From the point of view of the foundation's resistance, there are two extreme situations to be avoided: ultimate shear strength (to reach the ultimate bearing capacity of the foundation as a whole) and sliding stability (both for the contact of the dam at the foundation level as well as for the discontinuities of the rock mass). In this paper, a method to calculate the ultimate bearing capacity (qh) of a double curvature arch dam foundation is applied and the obtained safety factors are analyzed. The rock media is considered to be homogeneous and isotropic.
Beginning with the earliest geotechnical documents and up to the present, how to determine the loads that cause failure in a rock mass is very controversial and is subjected of great debate.
Several theories have been proposed, both in Spain as well as in other countries of our geographic and technological surroundings. Almost all of these theories are based on empirical considerations.
Amongst the failure laws found in literature, Hoek & Brown (1980) criterion is the most used and recommended to reproduce the response of a plastified rock mass as a whole. Otherwise, Serrano & Olalla (1994) methodology provides a theoretical framework and includes the main factors to determine, firstly the ultimate bearing capacities and secondly, the values of the safety factors obtained.
