oa Mini-seismic Methods for In-situ Rock Characterisation in Underground Facilities and Tunnels

BGR developed a bundle of ultrasonic and seismic methods, which we call Mini-Seismic Methods (MSM), for a comprehensive in-situ rock characterisation. Methods are applied in single boreholes, between two or more boreholes, along or between drifts and as a combination of borehole and drift based methods. Furthermore, for the characterisation of evolution processes of rock parameters (e. g. EDZ/EdZ creation and sealing) targeted repetitions or long-term monitoring measurements are applied ( Schuster et al. 2017 ). MSM are quick employable, robust and cheap tools which allow a reliable access to relevant basic geomechanical rock properties. For high spatial resolution boreholes are indispensable. MSM were applied in different potential host rocks for radioactive waste disposal in Europe. Piezoelectric transducers are used as receivers. As ultrasonic or seismic sources piezoelectric actuators and different impact tools are used. Transient recorders with up to 160 channels and up to 25 MS/s and dynamic ranges of 24 bit are used as recording systems.