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Journal ArticleDOI

Strength of a Model of Jointed Rock

TL;DR: In this paper, triaxial compression tests were carried out on idealized samples containing sets of preformed discontinuities inclined at various angles to the sample axes, and four major modes of failure were: axial cleavage fractures at low confining pressures, shear failure through the plaster and across joint planes, slip on joint planes and ductile failure.
Abstract: In an attempt to extend the presently limited state of knowledge of the strength of jointed rock masses, triaxial compression tests were carried out on idealized samples containing sets of preformed discontinuities inclined at various angles to the sample axes The 4 in by 4 in by 8 in samples were built up from one in cubes of a high strength gypsum plaster Triaxial tests were carried out on 5 sample types at each of 5 confining pressures in the range of 0 to 2000 psi The four major modes of failure were: (1) axial cleavage fractures at low confining pressures, (2) shear failure through the plaster and across joint planes, (3) slip on joint planes, and (4) ductile failure The strengths of block-jointed samples failing by mode (2) were less than those of the corresponding unjointed samples At the higher confining pressures of mode (4), the strengths were higher than those of the unjointed samples and were unaffected by joint orientation Friction parameters determined from tests in which mode (3) applied were the same as those determined for the plaster in direct shear tests Mohr's circle envelopes were curved, and could be described by a power law in which the normal stress index varied with joint orientation
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Journal ArticleDOI
TL;DR: In this paper, a simple empirical failure criterion is presented and its application in engineering design is illustrated by means of a number of practical examples, and the authors summarize some of the basic information upon which such simplifying assumptions can be made.
Abstract: Jointed rock masses comprise interlocking angular par- ticles or blocks of hard brittle material separated by discontinuity surfaces which may or may not be coated with weaker materials. The strength of such rock masses depends on the strength of the intact pieces and on their freedom of movement which, in turn, depends on the number, orientation, spacing and shear strength of the discontinuities. A complete understanding of this problem presents formidable theoretical and experi- mental problems and, hence, simplifying assumptions are required in order to provide a reasonable basis for estimating the strength of jointed rock masses for engineering design purposes. This Paper summarizes some of the basic information upon which such simplifying assumptions can be made. A simple empirical failure criterion is presented and its application in engineering design is illustrated by means of a number of practical examples. Des masses jointives de rochers comprennent des particules angulaires enchevetrees ou des ...

641 citations


Cites background from "Strength of a Model of Jointed Rock..."

  • ...Lama and Vutukuri (1978) have presented a useful summary of the results of model studies carried out by John (1962), Muller and Packer (1965), Lajtai (1967), Einstein et al (1969), Ladanyi and Archambault (1970, 1972), Brown (1970), Brown and Trollope (1970), Walker (1971) and others....

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Journal ArticleDOI
TL;DR: In this paper, the authors present the results of biaxial tests performed on physical models of rock with non-persistent joints, and the failure modes and maximum strengths developed were found to depend on, among other variables, the geometry of the joint systems, the orientation of the principal stresses and the ratio between intermediate stress and intact material compressive strength (σ2/σc).

260 citations

Journal ArticleDOI
TL;DR: In this article, a modified non-linear form of Mohr-Coulomb strength criterion has been suggested in order to overcome two major limitations of this criterion; first, it considers the strength response to be linear, and, secondly the effect of the intermediate principal stress on the strength behaviour is ignored.

209 citations

Journal ArticleDOI
TL;DR: In this article, a large number of uniaxial compressive strength (UCS) tests were conducted on the specimens of jointed block mass having various combinations of orientations and different levels of interlocking of joints.

154 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of joints in the rock mass is taken into account by a joint factor, which is incorporated in a non-linear FEM code to represent the equivalent continuum analysis.

135 citations