Effect of blast vibrations on the stability of cemented rockfill

Emad, Muhammad Zaka; Mitri, Hani S.; Henning, John G.

doi:10.1080/17480930.2012.707527

Cited by 27 publications

(15 citation statements)

References 2 publications

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“…The results of the dynamic model present static stress state after completion of the dynamic analysis. Failure condition for this analysis is development of tensile stress as used by Doerner (2005) and Emad et al (2012).…”

Section: Resultsmentioning

confidence: 99%

“…Yu and Counter (1983) and Yu (1992) concluded that a safety factor of 2.5 can be employed to increase strength of CRF to withstand dynamic loading from blasting. In a recent study by Emad et al (2012), the effect of different simulated blast loads was examined through a detailed numerical model parametric study. It has been shown that CRF failure could be initiated by blast vibrations.…”

Section: Introductionmentioning

confidence: 99%

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Effect of blast-induced vibrations on fill failure in vertical block mining with delayed backfill

Emad

Mitri

KellyCecile³

2014

Can. Geotech. J.

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Numerical modelling has long been used as a powerful tool for geomechanics mine design and analysis of such problems as ore dilution. Open stoping mining method with delayed backfill is generally employed for mining steeply dipping tabular ore deposits. Several authors reported that consideration of production blast vibrations on adjacent, exposed backfill faces is crucial for the effective backfill design for minimum ore dilution due to fill failure. In this study, it is shown that blast vibrations can be characterized with dynamic numerical modelling. A FLAC 3D dynamic numerical model has been developed for a typical layout of a secondary stope that is being mined next to a previously mined and backfilled primary stope. The numerical simulations are validated by comparing predicted failure geometry with laser-surveyed stope profiles obtained with a cavity monitoring system. It is shown that blast-induced vibrations can be a primary cause for wedge-type failure of the backfill face.Résumé : La modélisation numérique est utilisée depuis longtemps comme un outil puissant pour la conception géomécanique minière et l'analyse de problèmes tels que la dilution du minerai. La méthode d'exploitation à chambres ouvertes avec remblayage reporté est généralement utilisée pour le minage de gisements tabulaires à pente abrupte. Plusieurs auteurs ont mentionné qu'il est crucial de considérer les vibrations causées par les sautages de production sur les faces de remblai adjacentes et exposées, ceci afin de concevoir efficacement le remblayage pour minimiser la dilution du minerai causée par la rupture du remblai. Dans cette étude, il est démontré que les vibrations des sautages peuvent être caractérisées par la modélisation numérique dynamique. Un modèle numéri-que dynamique avec FLAC 3D a été développé pour représenter un chantier secondaire typique qui est miné à côté d'un chantier primaire préalablement miné et remblayé. Les simulations numériques sont validées en comparant la géométrie de rupture prédite avec des profils de chantiers sondés au laser avec un système de suivi de cavité. Il est démontré que les vibrations induites par les sautages peuvent être une cause principale des ruptures en coin de la face de remblai. [Traduit par la Rédaction] Mots-clés : remblai rocheux cimenté, modélisation numérique, minage en bloc vertical, surveillance de cavité.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of blast-induced vibrations on fill failure in vertical block mining with delayed backfill

Emad

Mitri

KellyCecile³

2014

Can. Geotech. J.

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“…The effects of opening inclination, third dimension and loads due to blasting may also alter the stress state of backfilled openings [20,22,38]. Additional work has been conducted and ongoing investigations are also underway to take these factors into account.…”

Section: Discussionmentioning

confidence: 99%

“…Previous investigations have shown that the finite difference code FLAC [37] can be used to help assess the behaviour of backfilled stopes [21,22,31,32,35,36,[38][39][40]. Figure 1 shows the reference FLAC model of a backfilled opening under plane strain conditions.…”

Section: Numerical Modelmentioning

confidence: 99%

Stress Ratios in Entire Mine Stopes with Cohesionless Backfill: A Numerical Study

Yang

Aubertin

2017

Minerals

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Evaluation of stress states in backfilled mine stopes (or similar openings), using arching theory, can be largely impacted by the value selected for the earth pressure coefficient, K = σ h /σ v . Recently, the current study's authors addressed the debate about the value of K near the opening center, based on Rankine's active coefficient (K a ) and at-rest coefficient (K 0 ). Here, stress ratios in vertical backfilled stopes are numerically assessed (in two dimension, 2D), considering both the independent and related backfill internal friction angle (ϕ ) and Poisson's ratio (ν). Emphasis is placed on the backfill state near stope walls, where local rotation of stresses occurs, so the coefficient (K) and principal stress ratio, K ps (= σ 3 /σ 1 ), should be distinguished. Parametric analyses indicate that values of K and K ps depend on the position and the relationship between ϕ and ν. Near the opening center, K (= K ps ) is close to K a when ν or ϕ is below a critical value; otherwise the value approaches K 0 , defined from ν. Near both walls, K ps is always close to K a , while K is near K 0 for related ν − ϕ cases and depends on their respective values for independent ν and ϕ . Additional simulations conducted with interface elements indicate that the stress ratios near the opening center line are insensitive to interface roughness and are almost identical to values obtained without interfaces, but the stress ratios near walls may change for less rough or smooth interfaces.

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“…Modified plastic cap model. Monotonous yield functions that pertain to I 1 (the first invariant of the stress tensor) have been widely used in soil models, or even in cement backfill models for blast loading, for example, the Drucker-Prager [24,[48][49][50][51][52][53], Mohr-Coulomb [17,43], and Lundborg [58,59,61,[64][65][66] criteria, and so on. Although they work reasonably well at low pressures, the performance of these types of models is not satisfactory in high pressure conditions.…”

Section: 22mentioning

confidence: 99%

A coupled chemo‐viscoplastic cap model for simulating the behavior of hydrating cemented tailings backfill under blast loading

Fall

2015

Num Anal Meth Geomechanics

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Summary Although the use of blasting has become a routine in contemporary mine operations, there is a lack of knowledge on the response of cement tailings backfills subjected to sudden dynamic loading. To rationally describe such a phenomenon, a new coupled chemo‐viscoplastic cap model is proposed in the present study to describe the behavior of hydrating cemented tailings backfill under blast loading. A modified Perzyna type of visco‐plasticity model is adopted to represent the rate‐dependent behavior of the cemented tailings backfill under blast loading. A modified smooth surface cap model is consequently developed to characterize the yield of the material, which also facilitates hysteresis and full compaction as well as dilation control. Then, the viscoplastic formulation is further augmented with a variable bulk modulus derived from a Mie–Gruneisen equation of state, in order to capture the nonlinear hydrostatic response of cemented backfills subjected to high pressure. Subsequently, the material properties required in the viscoplastic cap model are coupled with a chemical model, which captures and quantifies the degree of cement hydration. Thus, the behavior of hydrating cemented backfills under the impact of blast loading can be evaluated under any curing time of interest. The validation results of the developed model show a good agreement between the experimental and the predicted results. The authors believe that the proposed model will contribute to a better understanding of the performance of cemented backfills under mine blasting and contribute to evaluating and managing the risk of failure of backfill structures under such a dynamic condition. Copyright © 2015 John Wiley & Sons, Ltd.

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Effect of blast vibrations on the stability of cemented rockfill

Cited by 27 publications

References 2 publications

Effect of blast-induced vibrations on fill failure in vertical block mining with delayed backfill

Effect of blast-induced vibrations on fill failure in vertical block mining with delayed backfill

Stress Ratios in Entire Mine Stopes with Cohesionless Backfill: A Numerical Study

A coupled chemo‐viscoplastic cap model for simulating the behavior of hydrating cemented tailings backfill under blast loading

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