The different alternatives available today for modelling the mechanical/ hydromechanical behaviour of fractured rock masses, are initially discussed. Amongst these alternatives, a few have not attracted much attention, and constitute the main focus of the present paper. One of them concerns the representation of rock masses as an equivalent continuum. In this case, the so-called multilaminar model, introduced by Zienkiewicz & Pande (1977), was used to model the hydromechanical coupling in fractured rock masses. Another approach focused in the present paper, concerns the application of limit analyses techniques to rock mechanics problems, in special to fractured rock masses.


Les differentes alternatives aujourd'hui disponibles pour modeler le comportement mecanigue/hydromecanique des massifs rocheux fractures, sont discutees au debut. Entre ces alternatives, quelques-unes n'ont pas attire beaucoup d'attention, et constituent le foyer principal de la communication presente. Une d'elles concerne la representation des massifs rocheux comme un continu equivalent. Dans ce cas, l'ainsi dit, modele multilaminaire, introduit par Zienkiewicz & Pande (1977), a ete utilise pour modeler le couplage hydromecanique dans des massifs rocheux fractures. Une autre approche focalisee dans la communication presente, concerne l'application de techniques d'analyses de limites à des problèmes de mecanique des roches, en particulier à des massifs rocheux fractures.


Die verschiedenen, heute verfuegbaren Alternativen, um das mechanische/hydromechanische Verhalten von gekluefteten Felsen zu modellieren, werden an fangs erörtert. Unter diesen Alternativen, haben einige nicht viel Aufmerksamkeit auf sich gezogen, und machen den Hauptbrennpunkt des vorliegenden Referats aus. Eine von ihnen betrifft die Darstellung von Felsen als ein aquivalentes Kontinuum. In diesem Fall, wurde das durch Zienkiewicz & Pande (1977) eingefuehrte, sogenannte multilaminare Model benutzt, um die hydromechanische Kopplung in geklufteten Felsen zu modellieren. Eine andere, im vorliegenden Referat beleuchtete Annaherung betrifft die Anwendung von Grenzanalysentechniken auf Felsmechanikprobleme, insbesondere auf geklueftete Felsen.


Fig. 1 presents in a somewhat abridged form a possible subdivision of the models available today when one wants to analyse the mechanical behaviour of rock masses. The continuum type models are of course representative of the behaviour of intact rock or rock masses without joints. Equivalent continuum and descontinuum models are on the other hand suitable for the representation of fractured rock masses and constitute the main focus of the present paper. Equivalent continuum techniques for rock modeling have been traditionally the most popular way to represent the mechanical behaviour of rock masses. Presently, the availability of computer codes for the analysis of discrete media has pushed the use of such techniques. However, equivalent continuum techniques will always be appealing for practical use due to its convenience and practicality. Historically, equivalent continuum for fractured rock masses evolved from elastic (Amadei, 1983) to elasto-viscoplastic models (Zinkiewicz and Pande, 1977; Pande et al., 1990). The later models known as multi laminar are able to represent deformation mechanisms such as slip and separation along joint families. It is considered in the model that the joints are ubiquitous in the sense that their influence is felt in all points of the mass, Fig. 3 represents a rheological model of the multilaminar material. Furthermore, each rheological unit corresponding to a joint family is able to represent any constitutive law in the normal and shear directions. The total deformation of the medium is the sum of the corresponding deformations of all units (joint families plus intact rock). The multilaminar concept allows therefore the deformation characteristics of fractured rock: slip and separation along discontinuities; nonlinear constitutive laws in normal and shear directions.

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