Assessment of geomechanical properties of rock masses for preliminary support design of diversion tunnel at the Daroongar dam site

This paper presents the geomechanical parameters and the results of preliminary support design of the Daroongar diversion tunnel using some empirical and numerical methods. The rock mass rating (RMR), geological strength index (GSI) and rock mass quality (Q) systems were used for estimation of quality of rock masses properties for preliminary support design of tunnel. Also distinct element method (UDEC program) was used for stability analysis of the tunnel. Samples obtained from drilling were tested in the laboratory, included of uniaxial strength (UCS), deformation parameters, unit weight and porosity. In order to estimate strength parameters of rock mass (compressive strength of rock masses, tensile strength of rock masses, deformation modulus and Hoek-Brown constants) Hoek-Brown failure criterion was used.