THE BEARING CAPACITY OF BASALTS AT

THE ATASU (TRABZON) DAM SITE

            This paper describes the results of the engineering geological investigations and bearing capacity studies carried out at a proposed Atasu Dam site in Turkey. Atasu Dam is a rock-filled dam which is expected to be constructed on the Galyan stream in the northern part of Turkey. The foundation rocks are volcanic rock, consisting of basalts and pyroclastics (namely tuff, agglomerate and breccia). Analysis was carried out in terms of rock mass classification, determination of rock mass strength parameters and bearing capacity using different empirical methods. Studies were carried out both in the field and in the laboratory. Field studies included engineering geology mapping, discontinuity surveying, core drilling and sampling for laboratory testing. Laboratory studies involved uniaxial, triaxial and non-destructive testing (seismic wave tests). Also, deformation parameters and unit weight of intact rock specimens were evaluated in the laboratory. Rock mass strength and modulus of elasticity of rock mass were determined using the Hoek-Brown empirical strength criterion. Rock mass classifications for the dam rock foundation were performed according to the RMR, Q and GSI systems. Stress distributions at dam site were determined using the finite element technique. Engineering geological assessment and bearing capacity estimation of the rock foundation indicated that no foundation stability problems are expected at the dam site. Finally, to estimate the bearing capacity of basalts different empirical equations were used and compared.

Key Words: Basalt, Bearing Capacity, Hoek-Brown Empirical failure criteria