Recovery of undisturbed highly fractured bench scale (30 cm diameter) drilled samples for laboratory investigation

Investigation of the hydraulic parameters of fractured rock in the laboratory is often undertaken on a small scale (sample diameter to 10 cm) due to the difficulty of recovering undisturbed highly fractured rock samples. Usually such samples contain only one or at the most two discrete fractures. When investigating the hydraulic or mechanical parameters important for geotechnical applications (e.g. large-scale triaxial tests), it is necessary to have an understanding of the integrated effects of the fractures forming the fracture networks. In this paper, a method is presented whereby undisturbed samples with a diameter of 30 cm were recovered from a highly fractured porous rock mass and prepared for investigation of the fracture network properties in a laboratory. Most of the samples recovered contained several differently orientated fractures forming an interconnected network. The undisturbed nature of the recovered samples allows the hydrogeological and geotechnical characteristics of the fracture network to be investigated.