Mining of orebodies under shear loading Part 1 – case histories

He, Qingyuan; Kaiser, Peter K.; Mgumbwa, Juma; Thibodeau, Denis

doi:10.1179/1743286311y.0000000012

Cited by 24 publications

(21 citation statements)

References 10 publications

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“…As shown in Figures 8,9,11, and 12 microcracks propagate more from the outside of the pillar towards the pillar core and the bearing capacity also increases with increasing pillar size as shown in Figures 7, 10, and 13. In these figures the pillar strengths are 32.8 MPa, 33.2 MPa, and 34.2 MPa for pillar W/H ratios of 0.5, 1, and 1.5, respectively.…”

Section: Failure Characteristics Of Vertical Pillars With Differentmentioning

confidence: 89%

“…Model Overview. Following the procedure used by Suorineni et al [9,10] the effects of pillar dip angle, widthto-height ratio, and a certain stress ratio on the stability of pillars in a room-and-pillar mine are investigated using five width-to-height ratios, namely, 0.5, 1.0, 1.5, 2.0, and 2.5, at various degrees of orebody inclination, namely, 0 ∘ (Horizontal orebody resulting in vertical pillars), 10 ∘ , 20 ∘ , 30 ∘ , and 40 ∘ (orebody dip angles result in inclined pillars). A typical numerical model setup in RFPA2D is shown in Figure 2.…”

Section: Numerical Modeling Of Pillars Using Rfpamentioning

confidence: 99%

“…Ghasemi and Shahriar [8] proposed a new coal pillar design method. Suorineni et al [9,10] developed new knowledge on why pillars in ore bodies in shear are more prone to catastrophic failures than would normally be expected. They introduced the concept of shear loading in orebodies and pillars.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading

Tianhui

Wang

et al. 2016

Shock and Vibration

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Severe damage occurs frequently in mine pillars subjected to shear stresses. The empirical design charts or formulas for mine pillars are not applicable to orebodies under shear. In this paper, the failure process of pillars under shear stresses was investigated by numerical simulations using the rock failure process analysis (RFPA) 2D software. The numerical simulation results indicate that the strength of mine pillars and the corresponding failure mode vary with different width-to-height ratios and dip angles. With increasing dip angle, stress concentration first occurs at the intersection between the pillar and the roof, leading to formation of microcracks. Damage gradually develops from the surface to the core of the pillar. The damage process is tracked with acoustic emission monitoring. The study in this paper can provide an effective means for understanding the failure mechanism, planning, and design of mine pillars.

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Section: Failure Characteristics Of Vertical Pillars With Differentmentioning

confidence: 89%

Section: Numerical Modeling Of Pillars Using Rfpamentioning

confidence: 99%

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Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading

Tianhui

Wang

et al. 2016

Shock and Vibration

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“…Pillar inclinations lead to inclined loading conditions, and increasing pillar inclination reduce pillar strength [26,27]. In inclined pillars, the pillar sides towards the dip lead to the pillar failure.…”

Section: Effect Of Pillar Inclinationsmentioning

confidence: 99%

A Parametric Study of Blast Damage on Hard Rock Pillar Strength

Jessu¹,

Spearing²,

Sharifzadeh³

2018

Energies

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Pillar stability is an important factor for safe working and from an economic standpoint in underground mines. This paper discusses the effect of blast damage on the strength of hard rock pillars using numerical models through a parametric study. The results indicate that blast damage has a significant impact on the strength of pillars with larger width-to-height (W/H) ratios. The blast damage causes softening of the rock at the pillar boundaries leading to the yielding of the pillars in brittle fashion beyond the blast damage zones. The models show that the decrease in pillar strength as a consequence of blasting is inversely correlated with increasing pillar height at a constant W/H ratio. Inclined pillars are less susceptible to blast damage, and the damage on the inclined sides has a greater impact on pillar strength than on the normal sides. A methodology to analyze the blast damage on hard rock pillars using FLAC 3D is presented herein.

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“…The case studies were only based on one pillar and its failure mechanism, while the strength of the pillar was not evaluated to develop pillars in an inclined fashion. Two-dimensional finite-element numerical studies were conducted to evaluate the strength of hard-rock pillars under far-field principal stresses at different orientations, and it was concluded that the strength of the pillars with higher W/H ratios was highly affected by the orientation of the pillars [17,18]. Jessu and Spearing [19] conducted similar numerical studies to that of Suorineni [18] but with a finite difference code in a three-dimensional model to evaluate the strength and the failure mechanisms of pillars at different inclinations.…”

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confidence: 99%

Laboratory and Numerical Investigation on Strength Performance of Inclined Pillars

2018

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Pillars play a critical role in an underground mine, as an inadequate pillar design could lead to pillar failure, which may result in catastrophic damage, while an over-designed pillar would lead to ore loss, causing economic loss. Pillar design is dictated by the inclination of the ore body. Depending on the orientation of the pillars, loading can be axial (compression) in horizontal pillars and oblique (compression as well as shear loading) in inclined pillars. Empirical and numerical approaches are the two most commonly used methods for pillar design. Current empirical approaches are mostly based on horizontal pillars, and the inclination of the pillars in the dataset is not taken into consideration. Laboratory and numerical studies were conducted with different width-to-height ratios and at different inclinations to understand the reduction in strength due to inclined loading and to observe the failure mechanisms. The specimens’ strength reduced consistently over all the width-to-height ratios at a given inclination. The strength reduction factors for gypsum were found to be 0.78 and 0.56, and for sandstone were 0.71 and 0.43 at 10° and 20° inclinations, respectively. The strength reduction factors from numerical models were found to be 0.94 for 10° inclination, 0.87 for 20° inclination, 0.78 for 30° inclination, and 0.67 for 40° inclination, and a fitting equation was proposed for the strength reduction factor with respect to inclination. The achieved results could be used at preliminary design stages and can be verified during real mining practice.

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Mining of orebodies under shear loading Part 1 – case histories

Cited by 24 publications

References 10 publications

Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading

Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading

A Parametric Study of Blast Damage on Hard Rock Pillar Strength

Laboratory and Numerical Investigation on Strength Performance of Inclined Pillars

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