Time-dependent failure criterion for cemented paste backfills

Belem, Tikou; Fourie, Andries; Fahey, Martin

doi:10.36487/acg_rep/1063_13_belem

Cited by 15 publications

(5 citation statements)

References 15 publications

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“…Studies on Kidd tailings [33] and Williams tailings [35] found backpressures of at least 400 kPa were required for saturation. Therefore, tests by [36][37][38] at higher confining pressure levels would result in closer to saturated conditions. However, as shown in Figure 12, the mobilized shear resistance in undrained testing is not as high as in drained testing.…”

Section: Discussion: Application At Other Mine Sitesmentioning

confidence: 99%

“…This result is inconsistent with results of [33] which used backpressure saturation and pore water pressure measurements when testing the same Kidd CPB. The authors in [36] note that results from tests without backpressure saturation and pore water pressure measurements must be used carefully in design and could lead to overestimating backfill strength in some cases. Estimating plug strength requirements is such a case, where using c = 1 2 UCS would reduce the calculated strength (UCS) requirement by a factor of two.…”

Section: Discussion: Application At Other Mine Sitesmentioning

confidence: 99%

“…It is therefore recommended that the assumption c = 1 4 UCS continue to be used until it can be demonstrated that greater estimates of cohesion are warranted. Some authors [36][37][38] have tested CPB under undrained, but non-backpressure saturated conditions and without using pore water pressure measurements. In these cases, the induced suction during shearing at low confining stress levels leads to increases in effective confining pressure (to an unmeasured degree) and, therefore, artificially high interpretations of mobilized shear resistance, as shown in [34].…”

Section: Discussion: Application At Other Mine Sitesmentioning

confidence: 99%

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Required Plug Strength for Continuously Poured Cemented Paste Backfill in Longhole Stopes

Grabinsky

Bawden²,

Thompson

2021

Mining

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Continuously poured paste backfill dramatically improves underground mining efficiency through reduced stope cycle time and simplified logistics. For longhole stopes, a backfill “plug” is poured to a few meters above the undercut brow and must gain sufficient strength to prevent failure through the plug when the “main” pour begins. A novel, rational engineering design approach that determines the required plug strength is developed. The potential failure mechanism during continuous pouring is identified and the theoretical solution and its numerical validation/calibration are discussed. Four field case histories are then used, three of them involving continuous pours, to demonstrate the theoretical solution’s validity in back-analysis. These case studies are unique in the extent and quality of total stress and water pressure measurements made throughout backfilling. Additionally, comprehensive laboratory data are available to characterize strength development during binder hydration in the first few days, which are critical to the back-analyses. Results indicate that continuous backfilling is feasible with reasonably attainable backfill strengths at most mines. However, mines must undertake comprehensive early strength laboratory testing, and must carry out field measurements during the pour to ensure the placed backfill behaviour is consistent with the analysis assumptions.

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Section: Discussion: Application At Other Mine Sitesmentioning

confidence: 99%

Section: Discussion: Application At Other Mine Sitesmentioning

confidence: 99%

Section: Discussion: Application At Other Mine Sitesmentioning

confidence: 99%

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Required Plug Strength for Continuously Poured Cemented Paste Backfill in Longhole Stopes

Grabinsky

Bawden²,

Thompson

2021

Mining

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“…These eco-binders can contain treated biomass ashes, calcined clays, or any other industrial by-product that can be reused. For this purpose, the relative hydration index (Ha) was defined as follows (Belem & Sahi 2017;Sahi et al 2015, Belem et al 2010):…”

Section: Procedures For the Selection Of The Type Of Binding Agentmentioning

confidence: 99%

Mining with backfill: predicting backfill strength requirements, long-term behaviour, and placement

Belem¹

2023

Paste 2023: 25th International Conference on Paste, Thickened and Filtered Tailings

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The main challenge in mining with backfill is to design a flowable backfill capable of ensuring good stability of the backfilled stopes after placement and hardening. This would require, among other things, a good understanding of the physics (particle size distribution curve) and the mineralogy (presence of sulphides and/or clay minerals) of the mine waste, the correct determination of the required strength (based on the factor of safety), the correct definition of the rheological parameters (slump S, critical solids mass concentration %Cw-cr, adequate shear yield stress τY and viscosity µ), the proper selection of the backfill mix recipe (formulation taking into account the physico-chemical properties of the mixture ingredients), the correct design of the backfill retaining barricades (horizontal pressure), the good understanding of the hydromechanical properties (self-weight consolidation), the better control of the filling sequences (dissipation of the pore water pressure), the long-term compressive and shear strengths of the backfill, the reduction of the backfilling operation costs (possibility of reducing the amount of binder used), the prediction of the cemented rockfill and paste backfill strength.

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“…Cemented paste backfill (CPB) is an economic and environmental friendly technique applied in underground mining for supporting surrounding rock and replacing the pillar [1][2][3]. Over the years, the CPB technology has been widely adopted in the mining industry around the world [4][5][6]. CPB is usually composed of thickened or filtered tailings from concentrating mills, binding materials, and mixing water.…”

Section: Introductionmentioning

confidence: 99%

Temperature Effects on Rheological Properties of Fresh Thickened Copper Tailings that Contain Cement

Yong

Ruan

et al. 2018

Journal of Chemistry

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Cemented paste backfill (CPB) is an economic and environmental friendly technique applied in underground mining for supporting surrounding rock and replacing the pillar. However, little is known about the temperature effects on CPB in mines having a large temperature fluctuation. The main purpose of this research was to investigate the effect of temperature change on the rheological properties (e.g., shear stress and apparent viscosity) of CPB with copper mine tailings. Specifically, a series of rheological tests were conducted on 6 CPB samples using a Brookfield R/S+ Rheometer under various temperatures (2°C, 10°C, 20°C, 30°C, 40°C, and 60°C). Our results showed that both shear stress and apparent viscosity of these tailing samples increased with temperature rising from 2 to 60°C. Likewise, temperature has a significant impact on the Bingham yield stress of thickened tailings. The yield stress decreased from 122 Pa (2°C) to 112 Pa (20°C) and then increased to 152 Pa (60°C). Moreover, the pipeline transport pressure drop of CPB at various temperatures was calculated, illustrating an obvious effect on the paste pipeline transport. Compared with 20°C, the pressure drop under 2°C and 60°C increased by 11% and 22%, respectively. The results of this study indicate that the temperature plays an essential role in determining rheological properties of CPB and its engineering application in mines particularly with naturally fluctuating temperatures.

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Time-dependent failure criterion for cemented paste backfills

Cited by 15 publications

References 15 publications

Required Plug Strength for Continuously Poured Cemented Paste Backfill in Longhole Stopes

Required Plug Strength for Continuously Poured Cemented Paste Backfill in Longhole Stopes

Mining with backfill: predicting backfill strength requirements, long-term behaviour, and placement

Temperature Effects on Rheological Properties of Fresh Thickened Copper Tailings that Contain Cement

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