Analysis and design of an underground hard rock voussoir beam roof

Sofianos, A.I.

doi:10.1016/0148-9062(95)00052-6

Cited by 78 publications

(57 citation statements)

References 1 publication

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“…However, the numerical analyses by many other authors, for instance 7,8,13,19 , showed that the shape of the arch is parabolic. The shape of the compression arch is a parabolic of second degree when the span of the beam is more than 4 times of the beam thickness 7 and for short beams, second-degree parabolic shape is not valid.…”

Section: Discussionmentioning

confidence: 97%

“…Since voussoir beams are statically undetermined, a number of authors, for instance 7,8 , used numerical simulations to verify their assumptions in developing of the analytical techniques. In this paper, numerical simulations are also used to verify the analytical models developed in the previous sections.…”

Section: Numerical Verification Of the Voussoir Beam Modelsmentioning

confidence: 99%

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Analytical approaches for studying the stability of laminated roof strata

Shabanimashcool

2015

International Journal of Rock Mechanics and Mining Sciences

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Section: Discussionmentioning

confidence: 97%

Section: Numerical Verification Of the Voussoir Beam Modelsmentioning

confidence: 99%

Analytical approaches for studying the stability of laminated roof strata

Shabanimashcool

2015

International Journal of Rock Mechanics and Mining Sciences

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“…On the other hand, in the rock engineering literature, the line of thrust of a voussoir beam is assumed to be of parabolic shape (Evans, 1941;Beer & Meek, 1982;Brady & Brown, 1993;Sofianos, 1996;Sofianos & Kapenis, 1998;Diederichs & Kaiser, 1999b). The contact points between blocks were thus fitted using both a uniform catenary curve and a parabola for gravitational accelerations of 10g and 40g to extrapolate the line of thrust for the beams.…”

Section: Resultsmentioning

confidence: 99%

DEM modelling of a jointed rock beam with emphasis on interface properties

Boon¹,

Houlsby²,

Utili³

2015

Géotechnique Letters

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This paper compares analyses performed via the distinct element method (DEM), employing rigid blocks and compliant joints, with results using finite-difference software (FLAC) obtained previously by other researchers. The paper then examines the capability of the rigid-block DEM at modelling joints realistically, with emphasis on the moment transfer between blocks. The line of thrust from this analysis was found to fit well with the well-established uniform catenary curve and the parabola, which has been used extensively in the rock engineering literature. This is an important verification exercise that is still lacking in the literature, especially for the rigid-block DEM. Finally, a comparison is made between the DEM and experimental work carried out previously by other researchers. The previously reported laboratory data were reinterpreted to derive more accurate contact laws in both normal and shear directions. A strain hardening or continuously yielding model was adopted in the latter. The calibration approach is demonstrated. The numerical findings suggest that improved predictions of beam deflections can be obtained and the predicted horizontal thrusts are comparable to the results obtained by FLAC.

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“…Hence, the role of factor A is not only confusing but also mechanistically false because blocky rock masses are known to be unstable in tension [21,25,26] and more stable in moderate stress conditions. This was amply demonstrated in the case of the voussoir beam [35,36]. Intuitively, moderate stress conditions should give a stress factor A 4 1, rather than have no effect as is the case when A ¼ 1 for such conditions.…”

Section: Stress Factormentioning

confidence: 96%

The stability graph after three decades in use: Experiences and the way forward

2010

International Journal of Mining, Reclamation and Environment

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The stability graph was introduced approximately three decades ago for open stope design. Since then, it has gained wide recognition in open stope design around the world in hard rock metalliferous mining. Several developments have taken place following its initial inception aimed at improving its reliability in predicting the stability state of open stopes. These developments include redefinition of the stability graph number factors, the transition zones and addition of new factors. Various types of stability graphs have also emerged over the years for other purposes such as cablebolt layout design. The original database has also been significantly expanded from the 26 cases in 1981 to 483 cases to date. This article critically reviews the developments of the stability graph to date with the objective of: (1) Synthesising the scattered knowledge of these developments in the literature to a single source. (2) Creating awareness among potential users of the method, of the problems and risks arising from the uncoordinated developments in the method and the consequences of the lack of consensus in the choice of stability number factors. (3) Identifying areas for further research to improve the reliability of the method. (4) Finally, providing guidelines to inexperienced users and practitioners unaware of the various developments on the stability graph on when to use any one of the several stability graph types currently available. The article stresses that as an empirical method, the reliability of the stability graph method is largely dependent on the size, quality and consistency of the database. Hence, there must be consistency in the determination of the stability graph factors and accepted stope stability state transition zones. The present tendency for authors to arbitrarily choose between the original and modified stability number factors result in incomparable data that cannot be combined, while the different transition zones result in different interpretations of the stability state of stopes. The review also shows that there is need for factors that account for stope stand-up time, blast damage and gravity factor that is stress factor dependent. There is also a need to develop procedures for determining stability of open stope surfaces that are made of backfill. The inexperienced user and practitioner unaware of the various versions of the stability graph should be conscious of the different versions and types of stability graphs to make the appropriate choice for his/her design. The stability graph should also be used with caution, when applied to narrow vein orebodies because no version of the graphs accounts for orebody thickness in the definitions of the stability states.

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Analysis and design of an underground hard rock voussoir beam roof

Cited by 78 publications

References 1 publication

Analytical approaches for studying the stability of laminated roof strata

Analytical approaches for studying the stability of laminated roof strata

DEM modelling of a jointed rock beam with emphasis on interface properties

The stability graph after three decades in use: Experiences and the way forward

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