To evaluate the quantitative tunnel behavior influenced by characteristics of discontinuity, this paper executes the parametric study using 2 and 3-dimensional DEM analysis. First of all, this study finds that displacement and the stress of shortcrete are proportioned to frequency of joint and rockbolt axial force is adversely proportioned too. Secondly, it is found that the most sensitive input parameter used in Barton-Bandis(BB) model is residual friction angle. Finally, when joint sets are encountered at tunnel excavation face, to identify the most critical joint orientation is very crucial for a stability of tunnel.

La thèse a pour but d'etudier les influences sur la stabilite du tunnel, au niveau du reseau de la discontinuite et de la valeur de sa nature aquis par le projet recemment execute en vue de mener à l'analyse quantitative de cette stabilite, en appliquant chaque different paramètre comme la frequence de diaclase, la constante de resistance des modèles de Barton-Bandis(BB) ainsi que la relation entre le sens d'excavation du tunnel et le reseau de diaclase en 3 dimensions. En fait, cette etude nous a montre que la frequence de diaclase s'accroît proportionnellement au deplacement et à la contrainte du beton projete. L'angle de friction residuel s'est montre le plus sensible à la stabilite du tunnel parmi les modèles de BB. Aussi à travers l'analyse à 3 dimensions, il s'est verifie que si l'angle de pente du groupe de diaclase est horizontal entre l'axe du tunnel et la direction, il donne une influence importante sur le comportement du tunnel. En particulier, l'influence etait la plus importante sur un fond rocheux dont la diaclase horizontale est grande.

Um das quantitative Verhalten des Tunnels zu bewerten, eroertert dieses Papier eine parametrische Studie mit Hilfe der DEM Analyse. Auch wird hier eine zweidimensionale Analyse von Verbindungen verschiedener Frequenzen in der Gesteinsmasse, eine sensitive Analyse von allen der im Barton-Bandis-Modell (BB) genutzten Parameter und eine Dreidimensional-Analyse mit verschiedenen dreidimensionalen geometrischen Veteilungen von Verbindungen ausgefuehrt. Erstens: Die Studie findet heraus, dass Vedraengung und Druck im Shortcrete proportional zur Frequenz von Verbindungen und Axialkraft der Steinbolzen antiproportinal ist. Zweitens: Es wird herausgefunden, dass die am meisten Sensitiven der im BB-Modell angewendeten Eingaben die am Ende uebriggebliebenen Reibungswinkel sind. Und schliesslich wird herausgefunden, dass wenn Verbindungsteile an der Tunnelaushoelungsoberflaeche ausgemacht werden, fuer die Tunnelstabiltaet die Identifikation der meist kritischen Verbindungsorientierung sehr bedeutungsvoll.


All rock masses contain discontinuities which separate the blocks and cause a failure in rock mass (Hoek, 1998). Shi & Goodman (1985) and Kawamoto (1984) have presented a method to figure out movable key-blocks using limited equilibrium analysis. On the other hand, Cundall (1998) has developed distinct element method for the purpose of solving practical tunnel engineering problems considering various tunnel shapes and excavation steps, and Barton & Bandis (1983) have presented BB model enabling more realistic prediction of tunnel behavior. However, there has been little research with respect to an influence of joint properties on tunnel behavior (Bashin & Høeg, 1998).

From this point of view, this study is aimed at an introduction of the procedure to estimate quantitative discontinuity properties and an examination of the factors that could be expected to influence on a stability of the tunnel.

Understanding of discontinuity characteristics
Evaluation of geometrical discontinuity characteristics

Geometrical characteristics in discontinuous rock mass are represented of its shape, size, intensity, orientation, location and a stability of tunnel is mostly influenced by kinematical behavior of the blocks. Various methods for estimating geometrical discontinuity characteristics in stage of a site investigation and practical designing are used.

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