The Hishikari Gold Mine consists of epithermal vein type Au-Ag deposits, each of which has several veins standing almost in parallel each other and inclining 70 to 90 degrees. The veins have 1 to 3m widths and are extracted mainly by drifting and bench stoping with waste rock fill. The Hishikari has tried to optimise the stope dimensions by the Potvin's Stability Graph Method, which is well known as an easy and effective tool to design appropriate stope dimensions. The method, however, has some limitations of application due to its simplicity so that it has been used only in limited cases. The authors developed a new numerical approach, based on 2D FEM solution for the stability analysis. As a result, it has been possible to solve the Hishikari situation. The authors also introduce the concept of the design approach and compare the results obtained by using the approach with the database of the Stability Graph Method for validation.

La mine d'or Hishikari se compose de gisements d'Au-AG avec des types de filons epithermaux dont chacun a plusieurs veines qui sont presque parallèle les unes par rapport aux autres et sont inclinees de 70 à 90 degres. Les veines ont de 1 à 3 m de largueur et elles sont principalement extraites en creusant et en abattant des bancs de roches encaissantes. Hishikari a essaye d'optimiser les dimensions du chantier d'exploitation avec la methode de graphique de stabilite de Potvin, bien connue comme un outil facile et efficace pour avoir des dimensions de chantier d'exploitation appropriees. Toutefois, la methode a certaines limites d'application dues à sa simplicite de sorte qu'elle a ete utilisee seulement dans des cas limites. Les auteurs ont developpe une nouvelle approche numerique, basee sur la solution 2D FEM, pour l'analyse de stabilite. Par consequent, il a ete possible d'expliquer la situation de Hishikari. Les auteurs presentent le concept de l'approche et ils comparent les resultats donnes en l'employant avec la base de donnees de la methode de graphique de stabilite pour la validation.

Die Hishikari-Goldmine besteht aus Au-Ag-Ablagerungen mit epithermalen Adern, die jeweils mehrere Adern aufweisen, die mit einer Neigung zwischen 70 und 90 Grad nahezu parallel zueinander verlaufen. Die Adern haben eine Breite von 1 bis 3 Metern und werden ueberwiegend durch Vortrieb von Stollen und Bergversatz abgebaut. Hishikari hat versucht, die Abmessungen des Abbauorts durch das Potvins Stabilitatskurvenverfahren zu optimieren, das als einfaches und effizientes Mittel fuer die Erzielung angemessener Abmessungen des Abbauorts bekannt ist. Das Verfahren weist jedoch aufgrund seiner Einfachheit einige Anwendungsbeschrankungen auf, so dass es nur in einigen Fallen benutzt worden ist. Vor diesem Hintergrund haben die Autoren einen neuen numerischen Ansatz entwickelt, der hinsichtlich der Stabilitatsanalyse auf der 2D-FEM-Lösung beruht. Dadurch wurde es möglich, das Problem von Hishikari zu lösen. In diesem Dokument stellen die Autoren die Grundlagen des Ansatzes vor und vergleichen die erzielten Resultate durch Benutzung der Datenbank des Stabilitatskurvenverfahrens zur Validierung.


Every operating mine has a challenge to improve productivity and to reduce operating cost. Such improvement will depend strongly on selection of mining methods and their stope dimensions. In the last two decades, underground mining methods have been changing rapidly from the selective to the bulk methods such as open stoping, and the successful expansion of stope dimensions has been achieved by the spread of empirical methods represented by the Stability Graph Method (Potvin, 1988). Their advantages are in that one can give reasonable guidelines for stope dimensions based on the past site data and more easily understand their processes of evaluation without any special knowledge.

The Hishikari Gold Mine, located in southern Kyushu district of Japan, comprises epithermal gold veins standing almost vertically, which have been extracted by using drifting and bench stoping. Each vein usually has a width ranging from 1 to 4m. Generally, the veins contain not only many joints or discontinuities but also sometimes vugs. The bench stopes are ordinarily in the vicinity of such veins that may be sometimes already mined and backfilled (Fig.1). In general bench stoping, the Stability Graph Method can be one of powerful tools for evaluating stope stability.

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