The SMR (Slope Mass Rating) classification was introduced by ROMANA (1985) as a logical following to BIENIAWSKI RMR geomechanical classification. RMR (widely used in tunnels) is not of immediate use for slopes due to the fact that joints are a more governing parameter for stability in slope. SMR introduces four adjusting factor which allow a simple estimation of RMR correction factors. The paper summarises SMR methods, giving some guidelines for field work and some practical rules for the preliminary design of correction and support measures in slopes, according to SMR value. It includes toe ditches, nets, bolts, anchors, shotcrete and drainage.
La classification SMR ("Slope mass rating") a ete presente par ROMANA (1985) comm' un developement logique de la classification geomecanique, de BIENIAWSKI (RMR). RMR (frequenment utilise pour les tunnels) ne peut pas être aisement apliquee pour les talus a cause du fait que les diaclases sont Ie parametre determinant pour la stabilite des talus. SMR introduit quatre facteurs d' adjustement que la permettent une estimation simple des facteurs de correction RMR. Cette communication resume la methode SMR, donnant quelques recommandations pour Ie travail de champ et quelques regles pratiques pour Ie dessin preliminaire des mesure de correction et soutenement en talus, selon la valeur SMR. Cela includes tranchee de pied, fIets, boulons, ancrages, beton projecte et drainage.
Die SMR (Slope Mass Rating) KIassenordnung wurde bei ROMANA (1985) introduziert, als eine logische Erweiterung der BIENIAWSKI RMR geomechanischen Klassenordnung. RMR (weit benutzt in Tunnels) kann nicht direkt fuer Böschungen benutzt werden, da Kluften ein bestimmender Parameter der Böschungsstabilitat sind. SMR introduziert vier Anpassungsfaktoren die eine einfache Schitzung der RMR Berichtigungsfaktoren besorgen. Diesser Bericht bietet eine Zusammenfassung der SMR Verfahsrungsweisen an, und gibt sowohj Richtlinien fuer die Feldarbeit als auch praktische Regelungen fuer den Entwurf der Verbesserung- und Ausbaumassnahmen in Böschungen, alles im Einvernehmen mit dem SMR Wert. Der Bericht schliesst Fussgraben, Felsnagel, Felsankerungen, Spritzbeton und Dranung ein.
RMR "Rock Mass Rating" geomechanical classification (also called CSIR) was introduced and developed by BIENIAWSKI (1973, 1976, 1979). Two books (BIENlAWSKI, 1984, 1989) deal extensively with RMR (and other geomechanical classification systems). The most recent reference to RMR aplication to tunnels is BIENlAWSKI (1993). RMR has become a standard for use in tunnels and many professionals apply it to description of any rock mass. In the 1976 version, the "rating adjustments for discontinuity orientations" for slopes were: very favourable 0, favourable -5, fair -25, unfavourable -50, very unfavourable -60. No guidelines have been published for the definition of each class. STEFFEN (1976) stated that '35 slopes, of which 20 have failed, were classified, and the average values of cohesion and friction were used (to obtain) factors of safety with HOEK design charts for circular failure’. Fig. 1 shows Steffen's results, with ‘a definite statistical trend’. It was concluded that ‘the scope for using classification alone as a design method is still very limited’. No reference is given in Bieniawski (1984) for the use of the RMR classification in slopes. The reason for this lack of use is probably the extremely high values of the ‘adjustment rating value’, which can reach 60 points out of 100. A mistake in this value can supersede by far any careful evaluation of the rock mass, and classification work would be both difficult and arbitrary. In a majority of cases, the slope failures in rock mass are governed by joints, and develop across surfaces formed by one or several joints. Basic modes are summarized below. (i) Plane failures along prevalent and/or continuous joints dipping towards the slope. (ii) Wedge failures along two joints from different families whose intersect dips towards the slope.
