Stope design in Canadian hard rock mines is often carried out using the Stability Graph Method. However, this method does not account for the low confinement measured around stopes or quantify the amount of dilution associated with stope caving. A new approach to stope hangingwall stability is presented which consider the stress path the stope experiences and the effect of low confinement. A case study is used to illustrate the methodology.
La creation de chantier parmi les mines de roche dure au Canada est sou vent effectuee en utilisant la methode de graphique de stabilite. Cependant, cette methode n' explique pas le bas quantite de confinement mesuree entre les chanters ou attribuer à la quantite de dilution associee avec l' abattement de chantier. Dans ce papier est presente une nouvelle facon d' evaluer la stabilite d' eponts superieure qui prend en contexte Ie reseau de contraintes, l' experience acquise et l' effet d'une base quantite de confinement. Une etude de cas reel est utilisee pour expliques la method.
Die Bemessung von grossen Erzabbaukavemen (stopes) in kanadischen Hartgesteinsgruben wird haufig mit der Stabilitatsdiagrammethode durchgefueht. Diese Methode erklart jedoch nicht den wichtigen Einftuss niedriger radial Spannungen, die in der Nahe der Kavemenwande gemessen werden, noch bestimmt sie mit gentigender Genauigkeit das Volumen von Felseinbruechen. Eine neue Methode zur Stabilitatsbestimmung, die den Spannungsweg in Betracht nirnmt, wird dargestellt. Diese Methode wird hier an Hand einer Fallstudie erklart.
Canada's hardrock mining industry is confronted with the need to mine at ever increasing depths in a safe and efficient manner. Yet, traditionally, mining at depth incurs rock mass failures that impact the economic and safety aspects of a mine. Today, many mines are attempting to conduct risk analyses to help them assess the risks of mining at depth. In order for these attempts to be successful, a thorough knowledge of the geomechanics failure process and the factors that control or alleviate it are required. Hence, a fundamental understanding of the factors that affect rock mass failure is needed to develop technology that can be used to quantify the geomechanics risk of mining at depth.
Geomechanics instability and associated risk is traditionally quantified by comparing the stress to strength, i.e., a safety factor against failure. However, around mining stopes a single safety factor seldom meets the needs of the operator (Fig. 1). For example when excavating the topsill and bottomsill drifts the safety factor must be adequate to protect the workers, while during the non-entry (Figure in full paper) stoping operations between these sill drifts the operator needs to rely on the safety factor against unplanned dilution. Today there are many two and three dimensional numerical programs that allow the potential instability of any shaped underground opening to be assessed. However, determining the input parameters for these numerical programs, i.e., the rock mass strength, is still a challenging task. A far greater challenge, however, is the interpretation of the results from such analyses in terms of operators issues
