The numerical models have been calibrated using monitoring data from the existing tunnels comprised of displacement and stress data as well as qualitative data from liner condition mapping. This approach has allowed us to move around the production development geometry and introduce the appropriate geological conditions.
#Man made let in fish language in flac3d 5.0 code#
The modelling process utilises FISH code to import the complex geology model developed in LeapFrog and the isotherms provided by Cameco and their frozen ground consultant. The complexity increases with different ground support and liner material, limited clearance for the jet-boring machine, and a narrow pillar width. Using Itasca code FLAC3D, SRK has modelled the volumetric expansion brought on by the freeze and interactions with the tunnels below. SRK’s team is modelling the existing development and ground design to develop a more resilient design that does not interrupt the jet boring of the orebody. This has resulted in interruptions to jet boring operations and significant expense to rehabilitate the damaged production drives. These high and unevenly distributed stresses, combined with the highly variable geology and its contrasting physical properties, are adversely affecting the NATM production drives. The large mass of frozen ground induces stresses and associated displacements that vary depending on the rock type, alteration, and water content due to volumetric expansion that occurs during the state change. The ore is extracted above the development using an innovative method by jetboring 5m diameter stopes. The project presents unique challenges, most notably the extreme variations of rock strength from moderate (50 MPa) to weak (less than 5 MPa), and a largescale artificial freeze from the surface that encapsulates the orebody. This was critical for developing numerical models of the production drifts, which are located in highly variable geology – strong rock to weak clay alteration – and interactions from the overlying artificially induced ground freeze.
SRK conducted geotechnical and structural geology reviews, which led to refining the existing structural and alteration model. The SRK Vancouver Rock Mechanics team has been working at Cameco’s underground Cigar Lake Uranium Mine providing advanced multidisciplinary geotechnical modelling since the summer of 2015.