Friction of Rocks and Stability of Rock Slopes

Jaeger, J. C.

doi:10.1680/geot.1971.21.2.97

Cited by 292 publications

(84 citation statements)

References 17 publications

(33 reference statements)

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“…This suggestion is supported by the observations made on clay-infilled joints in this study. Of course, the stick-slip behaviour of rock surfaces is also influenced by the relative stiffnesses of the sample and the loading system (Jaeger, 1971).…”

Section: Shear Behaviour Of Sawtoothed Jointsmentioning

confidence: 99%

“…When the joint surfaces become weathered, the intact joint surfaces will lose contact. Therefore infilled rock joints are likely to be the weakest elements in a rock mass, and can have a dominant influence on its shear behaviour because of the low frictional properties of the infill (Jaeger, 1971;Ladanyi & Archambault, 1977;de Toledo & de Freitas, 1993;Brady & Brown, 2004). However, some infilled joints gain strength over time owing to bonding and consolidation, although these joints may be weakened again upon subsequent joint movement .…”

Section: Introductionmentioning

confidence: 99%

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Shear strength model for overconsolidated clay-infilled idealised rock joints

2008

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Saturated infilled joints can contribute to the instability of rock masses during undrained shearing. This paper reports an experimental investigation into the effect of the overconsolidation of infilled rough joints on undrained shear behaviour. A revised model is presented for predicting the shear strength of rough infilled joints on the basis of experimental tests carried out on idealised sawtoothed joints with natural silty clay as the infill material. Tests were conducted under consolidated undrained conditions in a high-pressure triaxial apparatus on joints having a dip angle of 608. Pore pressure development in the infill materials was monitored. The results show that the effect of asperities on shear strength is significant up to a critical asperity height to infill thickness ratio (t/a), whereas the shear behaviour is controlled by the infill alone beyond this critical value. The proposed model for predicting the shear strength of rough infilled joints describes how the OCR influences the shear strength, pore water pressure development, and critical t/a ratio.

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Section: Shear Behaviour Of Sawtoothed Jointsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Shear strength model for overconsolidated clay-infilled idealised rock joints

2008

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“…Jaeger (1971), in discussing failure criteria for rock, comments that 'Griffith theory has proved extraordinarily useful as a mathematical model for studying the effect of cracks on rock, but it is essentially only a mathematical model; on the microscopic scale rocks consist of an aggregate of anisotropic crystals of different mechanical properties and it is these and their grain boundaries which determine the microscopic behaviour'.…”

Section: Strength Of the Intact Rockmentioning

confidence: 99%

Strength of jointed rock masses

1983

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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 enchevêtrees ou des blocs de matiére dure et cassante séparés par des surfaces discontinues enrobées ou non de matiéres de moindre résistance. La résistance de masses rocheuses de ce genre dépend de la résistance des morceaux intacts et de leur liberté de mouvement, qui sont fonctions elles mêmes du nombre, de l'orientation, de I'icartement et de la résistance à la rupture au cisaillement des discontinuites. La compréhension compléte de ce probléme presente des difficultés considérables d'aspect théorique et expérimental, de sorte que des hypotheses simplificatrices sont nécessaires pour avoir une base raisonnable sur laquelle on peut estimer la resistance des masses jointives de rochers en vue de la construction. Cet article résume quelques-unes des données de base sur lesquelles de telles hypothéses simplificatrices peuvent être faites. Un critére de rupture empirique de nature trts simple est donné, son application à la construction étant illustrée au moyen dun certain nombre d'exemples pratiques.

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“…( Ces éléments, mais surtout la dilatance, ont été intégrés assez tôt dans les principaux modèles de résistance au pic développés par Patton (1966), Ladanyi et Archambault (1970), Jaeger (1971) et Barton (1973). Cependant aucun de ces modèles ne comporte de paramètre morphologique rigoureusement établi pour une surface irrégulière.…”

Section: Résuméunclassified

Validation d'un modèle de comportement mécanique pour les fractures rocheuses en cisaillement /

Flamand¹

2000

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In order to validate a model for the mechanical behaviour of sheared fractures in rock, we executed three series of direct shear tests applying three different levels of constant normal stress, to different tangential displacements and in four directions. These shear tests were performed on numerous mortar casts of a natural fracture from the Guéret granite (in France). Each cast was used only once (given CTN and U). From shear test results (strength and dilatancy) and the damaged casts, we examined the interactions between shear parameters, shear strength, dilatancy, initial morphology and strength of the fracture walls, as well as damage of the asperities.The initial morphology of the fracture walls was analysed from roughness profiles. Roughness indices, statistical distributions of angularities and variograms of elevation were calculated from the data obtained from the roughness profiles. Analysis of this data indicates that roughness indices do not all evolve in the same way during the damage process. The variograms obtained before and after the shear tests show evidences of degradation, but this data could not be incorporated in the models. However the statistical distributions of angularities, easily calculated for the apparent (2D) angles, were introduced in one model.The progressive degradation of the fracture walls was studied from the profile traces and image analysis data. The trace of the roughness profiles demonstrated the effect of the fracture walls strength and of the deposition of material from one wall to the other. The image analysis of the damaged walls showed that the shape and location of damaged zones depend on the shear direction, with regard to the morphological structures of the walls.Shear strength modelization produced three models that are applicable respectively to the pre-peak, peak and post-peak phases. The developed equations permit the incremented calculation on the shear strength with respect to the tangential displacement. Since many phenomena and parameters act on the shear strength, the three equations that we developed imply the calculation of many other parameters (e.g. a vo , a csp , i p , U p , i and

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Friction of Rocks and Stability of Rock Slopes

Cited by 292 publications

References 17 publications

Shear strength model for overconsolidated clay-infilled idealised rock joints

Shear strength model for overconsolidated clay-infilled idealised rock joints

Strength of jointed rock masses

Validation d'un modèle de comportement mécanique pour les fractures rocheuses en cisaillement /

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