Corkum, Andrew

Permanent URI for this collectionhttps://hdl.handle.net/10222/72235

Andrew Corkum

Associate Professor
Email: andrew.corkum@dal.ca

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Open Access
Variation of horizontal in situ stress with depth for long-term performance evaluation of the Deep Geological Repository project access shaft
(Elsevier, 2018) Corkum, AG; Damjanac, B; Lam, T
A site characterization program was carried out for a proposed Deep Geological Repository (DGR) project for Ontario Power Generation's (OPG) low- and intermediate-level nuclear waste repository near Kincardine, Ontario. The repository is proposed to be constructed at approximately 680 m below ground surface within the competent argillaceous limestone of the Cobourg Formation. The in situ stress state at the project site will have significant impact on both the short- and long-term performance of repository openings, such as emplacement caverns and access shafts. As part of the site characterization program, an evaluation of the in situ stress state of the project site was conducted which consisted, primarily, of a review and synthesis of existing stress measurements conducted at various locations throughout Ontario and the midwestern U.S. Based on geomechanics data from deep boreholes and stress measurement data, a simplified FLAC3D model of the full stratigraphic profile was developed and used to simulate the influence of regional tectonic strain in the project area. In particular, this method takes into account the rock properties, such as stiffness, for discrete units at the DGR site. The model was calibrated on the basis of in situ stresses measured at Norton Mine, in a similar geological environment as the DGR site, and with site-specific borehole televiewer observations (i.e., breakouts). The model-predicted horizontal in situ stress profile showed general agreement with the observations and also showed the significant influence of discrete rock unit stiffness.
Open Access
Analysis of a rock slide stabilized with a toe-berm: A case study in British Columbia, Canada
(Elsevier, 2004) Corkum, AG; Martin, CD
Practical experience has shown that slope movement can be controlled by the placement of a berm near the toe of the moving mass. During construction of the Revelstoke project (British Columbia, Canada), excavation of a large highway rock cut triggered movement of a 250,000 m 3 rock slide. A 15,000 m 3 toe-berm was used as a temporary measure to control the displacements of the slide and allow permanent remedial measures to be completed. The rock slide was extensively investigated and monitored. The Sarma limit equilibrium method and the three-dimensional distinct element program, 3DEC were used to investigate the stabilizing effect of the toe-berm on the slope deformations. In addition, 3DEC was used to investigate the effect of internal discontinuities on slope displacements. The numerical model responded in a manner that is in general agreement with field observations and supported the observations that a small toe-berm can be an effective remedial measure in controlling slope displacements.
Open Access
Numerical Analysis of Longwall Mining Layout for a Wyoming Trona Mine
(Elsevier, 2016) Corkum, Andrew; Board, Mark
At Solvay Mine, located in southwestern Wyoming, a subhorizontal trona seam is mined at depths of between 460-490 m using mechanized room-and-pillar and longwall mining methods. The stratigraphy at the mine generally consists of horizontally laminated (i.e., bedded) sedimentary rocks comprised mostly of shales and sandstones with significantly contrasting mechanical properties. Most notably, a 43 – 82 m-thick massive, brittle sandstone unit (Tower Sandstone) is located approximately 100 m above the mining level. The Tower Sandstone unit has a tendency to promote stress arching within the overburden rock that can bridge over panel-scale mine instabilities and can lead to violent multi-panel collapse failure. One such violent collapse is the well-documented 5.1 magnitude seismic event due to a 1 x 2 km multi-panel failure on February 3, 1995. It has proven difficult to account for this arching behaviour with conventional mine design methods, such as the tributary area method. Therefore, over the past two decades or more, Solvay Mine has been utilizing numerical modelling techniques along with field instrumentation/monitoring as part of an integrated program to gain an enhanced understanding of the complex response of the overlying stratigraphy (i.e., arching) to mining. In 2005 and 2006, several longwall panels in the northwest and southeast areas of the mine were instrumented and monitored during mining. Two- and three-dimensional numerical models, using FLAC and FLAC3D, were developed and calibrated on the basis of the instrumentation data, and these models were then used for mine design verification (e.g., pillar and panel dimensions). This mining case study illustrates the complex excavation response due to the contrasts in stratigraphy at Solvay Mine and presents a numerical modelling study that captures the dominant aspects of these conditions. In addition, the practical use and role of numerical modelling and instrumentation within an integrated mine design methodology is demonstrated.

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