Accounting for intrablock structures at rockmass and laboratory specimen scales

ABSTRACT: For deep excavations in heterogeneous complex rockmasses that contain hydrothermal veins and other types of intrablock structures, conventional field characterization and laboratory measurement protocols that were developed for numerical geotechnical design of homogeneous rockmasses are no longer adequate. In this paper, rockmass characterization methodologies in the field and laboratory for complex rockmasses are discussed, with particular emphasis on the importance of mineralogical investigation for both the matrix and vein materials. The opportunities for continuum and discontinuum numerical modelling are also discussed based on the availability of different field or laboratory data. Finally, a case study of unconfined compressive strength laboratory tests on three lithological units from the Legacy skarn deposit is presented to demonstrate both weakening and strengthening influences that intrablock structures can have on stiffness and peak strength properties.