ABSTRACT: For any effective engineering design procedure in rock, the properties of the rock mass must be estimated. For underground mining and civil work, rock mass classification is one of the most widely used estimate of rock mass properties. Design procedures often require approximations of the deformation properties and failure behaviour. These parameters are often estimated based on rock classification. Commonly used classification systems, such as the NGI rock quality "Q" system, unfortunately require rock mass information which is subjective in nature. This paper introduces" several more rigorous approaches for obtaining and analyzing data to remove some of the subjectivity inherent in present methods of rock characterization.
RÉSUMÉ: Le dimensionnement des ouvertures dans les massifs rocheux depend de leurs proprietes qui doivent être evaluees en premier lieu sur place. Pour les ouvrages souterrains tant civils que miniers, les systèmes de classification des massifs rocheux constituent des outils qui sont largement utilises pour arriver à cette fin. Ces systèmes (tel le système "Q" du NGI) sont composes de paramètres qui sont dans leur nature propre, très subjectifs à determiner. Cet article presente plusieurs methodes pour obtenir et analyser des donnees de façon à diminuer la subjectivite inherente aux systèmes de classification actuels.
ZUSAMMENFASSUNG: Um einen effektiven Entwurf fur den Abbau im Fe1s zu entwickeln, mussen die mechanischen Eigenschaften des Felsmassives eingeschatzt werden. Entwurfsmethoden beruhen meistens auf einer Bestimrnung der Verformungs Charakteristiken und des Benehmens wahrend des Zerfal1s. Fe1smassiv Klassifizierungs Methoden,werden weitgehendst im Bergbauwesen eingesetzt um diese Fe1smassiv Eigenschaften bestimrnen. Übliche Klassifizierungssysteme wie das NGI "Q" System beruhen auf Information ueber den Fels, welcher meistens sehr subjektiver Natur ist. Die hier prasentierte Arbeit zeigt verschiedent Methoden auf, die Subjektivitat von der Sammlung,und der Analyse der Daten entfernt.
1 INTRODUCTION It has been recognized in the Noranda Geomechanics group that there is a general over emphasis placed on the value of sophisticated modelling and design techniques in the field of rock mechanics. Some estimate of overall rock mass properties is required for this work, but the quality of the input seldom justifies the effort spent in design. We have been increasing our effort in obtaining data which can be related to the overall properties of the rock mass and work has been focused in three main areas:Increasing the time and effort spent in field data collection.
Improving the techniques used in measuring the parameters important for rock mass characterization.
Improving the system used for storage, manipulation and interpretation of the field data collected.
Rock classification, such as the NGI "Q" system (Barton et al. 1974) and RMR system (Bieniawski 1976), are attempts to assess rock mass properties and express the rock condition as a number. It has been said, "If you can measure what you are speaking about, and express it in numbers, you know something about it" (Lord Kelvin). Classification systems Currently achieve half of this goal, they express the rock mass properties as a number, unfortunately much of the input in these systems is very difficult to measure.