Servo Controlled Shear Actuator for high accuracy determination of interlayer, fracture and vein stiffness and strength for waste storage and deep mining applications

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The research program to be supported is that of Dr. Diederichs and Dr. Hutchinson at Queen's University. The primary research of Dr. Diederichs involves early damage detection in rock under a variety of loading and boundary conditions as a predictor for long term performance adjacent to and around underground nuclear waste repositories. The equipment being requested here will form a critical cornerstone in the experimental work related to excavation damage around shafts, tunnels and caverns designed for long term storage of nuclear waste in sedimentary rock where planar fabric and bedding dominate behaviour. The long term stability and limiting permeability of the host rocks for such a repository depend on controlling the levels of damage development around the excavations during construction, operation and over the long term life of the repository. This research is aimed at quantifying the role of shear stiffness and strength of laminations within the host rock and the impact on Excavation Damage Zone (EDZ) development. The primary research of Dr. Hutchinson in collaboration with Dr. Diederichs is the integration of filled structures such as veins into rockmass strength estimation yield prediction in deep mining. Modern numerical tools can accommodate discrete features such as veins but the validity of behavioural properties incorporated in these models are not well understood. This equipment will allow determination of shear and normal mechanical properties for a wide range of structures and defects in the rock. The tests to be performed during the course of this research require a full time dedicated self-contained actuator/load frame with a high level of customizable control and flexible physical configuration for innovative direct shear and fracture testing. The equipment requested here is a servo-controlled shear loading frame with high-stiffness and state-of-the-art digital control technology that makes it possible to conduct pre and post-peak direct shear tests in combination with strain, acoustic and other measurements. Within the next 4 years 6-8 graduate students will use the system in a variety of projects including those discussed but also in a secondary capacity in a number of other projects.