An improved solution for sizing barricades made of waste rock to retain cemented paste backfill

Pengyu Yang, Marin Brochu-Baekelmans, Li Li, Michel Aubertin

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Mining Geotechnics

ABSTRACT: ed solution for sizing barricades made of waste rock to retain cemented paste backfill Pengyu Yang, Marin Brochu-Baekelmans, Li Li and Michel Aubertin Department of Civil, Geological and Mining Engineering École Polytechnique de Montréal, Montréal, QC, Canada ABSTRACT Stope backfilling is applied in many underground mines across Canada, Australia, China and elsewhere. To apply this technology, barricades usually have to be constructed in access drifts near draw points to hold the initially saturated backfill in place. Several cases of barricade failure reported in the literature indicate that their stability is a critical concern to ensure the successful backfilling of stopes. Typically, these barricades are made of materials having a high strength, such as bricks, concrete blocks, or reinforced shotcrete. An alternative method that is gaining popularity, particularly in some parts of Canada, is to construct the barricades with waste rock. Compared with conventional methods, these can be easier to build and more cost-effective. Analytical solutions have been proposed to design such waste rock barricades (WRB) by considering a limit equilibrium state for an idealized rectangular block shape. In practice however, WRB constructed in drifts have a shape that is close to a trapezoid. Because of this, the design based on the rectangular block solution may be overly conservative. Thus, there is a need to develop an improved solution, by considering a more realistic geometry for the barricades. This paper presents a limit equilibrium analysis to determine the required dimensions of trapezoidal WRB. The solution is obtained by dividing the barricade into a central rectangular part and two triangular portions. Sample calculations are made to illustrate the use of this modified solution and to present the effect of key influence factors on barricade design. Compared with the existing solution, the results indicate that, given the same conditions, the improved solution predicts a reduction of up to about 50% in the required amount of waste rock. RÉSUMÉ Le remblayage des chantiers est de plus en plus utilisé dans les mines souterraines au Canada, en Australie, en Chine et ailleurs. Cette technique implique la construction de barricades dans les galeries s pour retenir le remblai initialement saturé. Plusieurs cas de rupture de barricade avec des conséquences graves ont été rapportés, ce qui indique que leur stabilité est critique pour une utilisation sécuritaire du remblai. Typiquement, ces barricades sont construites de matériaux ayant une grande résistance telle des briques, des blocs de béton ou du béton projeté renforcé. Une alternative qui gagne en popularité, particulièrement au Canada, est e roches stériles. Comparées aux méthodes conventionnelles, ces barricades sont plus faciles et moins coûteuses à construire. Des solutions analytiques ont été proposées pour la conception de barricades de roches stériles (BRS) limite. Ces méthodes considèrent une barricade rectangulaire. Mais en pratique, une BRS a une forme trapézoïdale, et la solution considérant un bloc rectangulaire conservatrice. Il existe donc un besoin de développer une solution améliorée qui considère une géométrie plus réaliste de la barricade. Cet article présente une analyse à llimite pour trapézoïdale. La solution est obtenue en séparant la barricade en une section centrale rectangulaire avec deux triangles extérieurs. Des résultats de calculs sont présentés certains facteurs clefs qui influencent la conception des barricades. Les résultats comparatifs montrent que, pour les mêmes conditions, la solution modifiée peut réduire 50% le volume de roches stériles requis pour construire la barricade. 1 INTRODUCTION Backfilling is a common practice to support rock mass around underground mine stopes. The use of mining wastes as backfilling material can significantly reduce the surface disposal of these wastes, hence limiting their environmental impact (Aubertin et al. 2002; Benzaazoua et al. 2008). Prior to backfilling, barricades need to be constructed in access drifts near the draw points to prevent in-rush of the initially saturated fill. A number of barricade failures have been reported over the years (Bloss and Chen 1998; Grice 1998; Helinski et al. 2006; Sivakugan et al. 2006a, 2006b, 2013; Yumlu and Guresci 2007). Such failures can have catastrophic consequences, such as drift flooding, machinery damage and even human casualties. Hence, a critical engineering issue is to safely determine the size of the barricades, based on the pressures exerted by the backfill. Barricades have traditionally been made of porous brick walls allowing free drainage; concrete blocks and reinforced shotcrete mesh with drainage pipes are also used to build barricades (Sivakugan et al. 2006b; Sivakugan 2008; Hughes et al. 2010). The application of these techniques can however be costly and time consuming. Alternatively, barricades can be built with waste rock. Compared with more traditional methods, this technique can be easier and faster to implement, while the construction material (waste rock) is available at a lower cost when provided by the underground operations. Moreover, it further reduces the surface disposal of mining wastes.

RÉSUMÉ: mproved solution for sizing barricades made of waste rock to retain cemented paste backfill Pengyu Yang, Marin Brochu-Baekelmans, Li Li and Michel Aubertin Department of Civil, Geological and Mining Engineering

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Cite this article:
Pengyu Yang; Marin Brochu-Baekelmans; Li Li; Michel Aubertin (2014) An improved solution for sizing barricades made of waste rock to retain cemented paste backfill in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper185,author = Pengyu Yang; Marin Brochu-Baekelmans; Li Li; Michel Aubertin,title = An improved solution for sizing barricades made of waste rock to retain cemented paste backfill ,year = 2014}