ABSTRACT:

The methods of estimating the deformability, strength, thermal and hydraulic conductivities and thermal expansion coefficients of jointed rock masses are presented. They are based on a new approach to equivalent properties which can handle arbitrary joint orientations and numbers of joints or joint sets, and thus resolve the difficulties of determining the field scale properties of rock masses with complicate joint geometry. The commonly available properties of rock mass constituents, i.e. the joints and intact rock, are effectively combined in the equivalent rock mass properties formulated in three dimensions. The capability of the new approach for bridging the gap between different scales of observation in rock mass engineering is demonstrated in the example problems of underground excavations in jointed rock masses.

RESUME:

On presente les methodes qui estiment la deformabilite, la resistance, les conductivites thermiques et hydrauliques et les coefficients de l'expansion thermiques des massifs rocheux fractures. Les methodes sont basees sur une approche des proprietes equivalentes nouvelle qui peut mainier des orientations de joint arbitraires et des nombres des joints, et donc resout les difficultes qui determinent les proprietes d'echelle in-situ des massifs rocheux ayant une geometrie de-joint compliquee. Les proprietes disponibles communement des constituants des massifs rocheux, autrement dit les joints et la roche intacte, sont effectivement combinees dans les proprietes des massifs rocheux equivalentes. La capacite de l'approche nouvelle pour relier les bords de la brèche entre les echelles differentes d'observation en ingenierie des massifs rocheux est demontree dans les problèmes des excavations souterraines dans des massifs rocheux fracturùs.

ZUSAMMENFASSUNG:

Die Methode der Abschatzung von Verforrnungsvermögen, Festigkeit, thermischer und hydraulischer Leitfahigkeit und Ausdehnungskoeffizienten der gekluefteten Felsen Masse werden dargestellt. Die Methode beruhen auf einer neuen aquivalenten Eigenschaftsapproche, die freiwillige geklueftete Richtung und Nummern der gekluefteten Masse behandeln kann, und dann winden Schwierigkeiten ueber Bestimmung der Maβstabseffekte von Felsen Masse in situ. Die Nutzwendungseigenschaften der Felsen Masse, d.h. gekluefteter und intakter Felsen verbinden sich in der angesammelten aquivalenten Felsen Masse Eigenschaft. Die Fahigkeit der neuen Approche fuer Lösung des Unterschied zwischen verschieden Maβstab der Beobachtung in Felsen Masse Ingenieurkunst wird in Beispiele der Untergrund Aushohlungen in gekluefteten Felsen Massen dargestellt

1
INTRODUCTION

Rock masses in general contain a variety of discontinuities such as fissures, fractures, joints, faults, and bedding planes. Rock joints are the most common type of geologic features observed in almost all rock formations in the field and are considered most important in engineering rock mechanics. The transition of the scale of observation from a laboratory specimen to the full scale rock mass produces a number of intermediate scale rock masses having different structural conditions. Depending on the size and location, the internal structure of the rock mass varies and so do the properties. Furthermore, the rock mass properties are not universal but site specific, since the geometric characteristics of joints (density, orientation and size) in one site are seldom replicated in others. The mechanical, thermal and hydraulic properties of jointed rock masses are yet veiled in uncertainty, although the properties of the joints and surrounding intact rock are attainable individually through laboratory testings. This paper presents the approximate methods of estimating the deformability, strength, thermal and hydraulic conductivities and thermal expansion coefficients of jointed rock masses with arbitrary orientations and numbers of joints. The methods are based on a new equivalent property approach. This approach has the capability of handling a multitude of irregular, non-periodic joints and is distinguished from the conventional REV (representative elementary volume) concept, which has an applicability limited to regular joint patterns or a perfectly disordered (random) distribution of joints.

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