Estimating hydrocompression potential of mine spoils from a site in eastern Kentucky using dry unit weight and moisture content

Kalinski, Michael E.; Karem, Wayne A.; Little, Lauren

doi:10.1080/17480930.2010.488852

Cited by 6 publications

(7 citation statements)

References 3 publications

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“…The failures are often initiated at the base of spoil piles where the material can undergo significant slaking (disintegration) over time due to overburden pressure and water saturation. The spoil materials are typically composed of blasted fragments of mudstone, siltstone and sandstone [1]. The mean particle size of spoil is highly, ranging from fines to particles of size 0.5 m to 1.0 m depending on in-situ properties of overburden, blasting technique and equipment used.…”

Section: Introductionmentioning

confidence: 99%

A New Laboratory Model of a Slaking Chamber to Predict the Stability of on-Site Coal Mine Spoils

Gallage¹

2016

geomate

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Slope failures of spoil piles pose a significant safety risk in open-cut strip mining due to slaking over time due to overburden pressure and water saturation. Most spoil pile failures occur when the pit has been previously filled with water and then subsequently dewatered. It is important to understand how the mechanical properties of base spoil material are affected by slaking when designing safe spoil pile slope angles, heights, and dewatering rates. A new laboratory slaking chamber (360mm ID, 400mm high with 20mm wall thickness) has been designed and constructed to accommodate approximately 60 kg of spoil (unit weight, 18 kN/m3) and a simulated overburden pressure of 1000 kPa. Consolidation of the spoil can be measured through a linear variable differential transformer (LVDT) attached to the system. Using this apparatus, a fresh spoil material collected from a coal mine in Brown Basin Coalfield of Queensland, Australia was subjected to high overburden pressure (0 -900 kPa) under saturated condition and maintained over a period of time (0 -6 months) allowing the material to slake and successfully tested for classification, permeability, and strength properties. Results suggested that the slaking of saturated coal mine spoil increase with overburden pressure and the time duration over which the overburden pressure was maintained. Shear strength and permeability of spoil decreased with increase in spoil slaking.

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Section: Introductionmentioning

confidence: 99%

A New Laboratory Model of a Slaking Chamber to Predict the Stability of on-Site Coal Mine Spoils

Gallage¹

2016

geomate

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“…The determined hydrocompression strains in every condition is less than 5% which means that CMT has a degree of collapsibility classified as low to negligible despite of having plasticity. The amount of hydrocompression strain obtained is higher than the values obtained for non-plastic mine tailings [1] and within the range of values for mine spoils with low plasticity [13]. …”

Section: Effect Of Initial Moisture Contentmentioning

confidence: 79%

The Effect of Void Ratio, Moisture Content and Vertical Pressure on the Hydrocompression Settlement of Copper Mine Tailing

Adajar

Cutora²

2018

GEOMATE

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ABSTRACT:Copper mine tailing (CMT) has the potential to be used as embankment material but this waste material contains plasticity. Soils containing plasticity are highly reactive to any form of liquid and considered to have greater compressibility when exposed to water. As an embankment material, CMT is susceptible to different environmental condition which can cause significant settlement. One possible cause of volume loss is the compression due to wetting or hydrocompression. This study aims to determine the consolidation properties and hydrocompression settlement of waste materials with plasticity like copper mine tailing when used as embankment material. One-dimensional consolidation tests were performed on reconstituted specimens. The obtained consolidation properties indicate that CMT is very slightly compressible under over-consolidated condition to moderately compressible under normally consolidated condition. The hydrocompression settlement of CMT in relation to initial void ratio, moisture content and vertical pressure was investigated. The hydrocompression settlement increases with increasing pressure until the preconsolidation pressure is reached, then decreases with pressure beyond the preconsolidation pressure. Samples with lower density and initial water content less than its optimum exhibit greater hydrocompression settlement. The determined hydrocompression strain in every condition is less than 5% which means that CMT has a degree of collapsibility classified as low to negligible despite of having plasticity. CMT when used as embankment materials should be prepared with initial moisture content slightly more than its optimum, it should be in its very dense condition and preloaded with vertical stress more than its preconsolidation pressure to make hydrocompression strain negligible.

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“…Mine spoils do not exhibit consolidation settlement associated with the time-dependent dissipation of excess pore water pressure (Kalinski, Karem & Little 2010). Instead, the mechanisms are stress-induced deformation under added weight and collapse due to wetting of the mine spoil.…”

Section: Settlement Of Coal Mine Spoilmentioning

confidence: 99%

“…Arching was therefore considered not significant, as the fill width to height ratio was sufficiently low. Kalinski, Karem & Little (2010), in experiments to estimate the hydrocompression (collapse) potential of mine spoils from eastern Kentucky, found that saturation-induced settlement increased slightly with an increase in confining stress.…”

Section: Case Studies -Settlement Of Mountaintop Removal Spoilmentioning

confidence: 99%

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Bulking and Subsequent Self-Weight and Saturation Settlements, and Geotechnical Stability of High Coal Mine Spoil Piles

Kho¹

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To satisfy the ever increasing global and domestic demand for coal, many coal mine operators in Australia, with thick coal seams at depth, are investigating the feasibility of deep open pit mining. Pit depths of up to 500 m have been proposed, with projected spoil pile heights of up to 600 m. The increased thickness of overburden becomes a significant issue, as this increases the amount of spoil produced. Mine operators then have to decide where to place spoil in the early stages of mine planning. Therefore, the parameters on which decisions are made have to be determined up front, to accurately estimate the net present value costs necessary to prove the financial viability of deep open pit mining at a given site.The mechanisms that cause spoil volume change are: bulking, self-weight settlement, saturationinduced collapse and degradation, all of which act together to alter the shape and height of spoil piles.Thus, the understanding of these volume change mechanisms is critical to the design, sizing, geotechnical stability and cost estimation of an open pit coal mine.This thesis documents the research, funded by Australian Coal Association Research Program (ACARP) Project C19022, aimed at investigating the effects of settlement and strength of coal mine spoil. As part of the research, several mine sites were visited. Representative spoil samples were collected and were subjected to a comprehensive laboratory testing programme.Laboratory direct shear testing undertaken in two sizes, 60 mm square and 300 mm square, found that coal mine spoil materials are best characterised as having low cohesion (generally less than 10 kPa) and reasonably high friction angles (generally greater than 30°). On testing under dry conditions, the friction angle is typically in the range from 27 to 35°, while on testing under wet conditions, the friction angle decreases to the range 20 to 34°. Wetting up is seen to cause some reduction in strength, especially for the weakly-cemented and highly plastic spoils.Laboratory compression tests were performed on two sizes: the standard 76 mm diameter oedometer, capable of stresses up to 1 MPa, and the 150 mm diameter high stress oedometer, capable of stresses up to 10 MPa. Self-weight settlement of initially dry spoil was found to be up to 45% of initial height iii at 10 MPa stress. Of this, about 80% is expected to occur during placement and is thus not 'seen'.Collapse settlement on wetting up was found to cause additional settlements of up to 15% at stresses of about 500 kPa, decreasing to about 5% at 10 MPa stress. Negligible further collapse is expected after a collapse event, since water merely fills the voids between particles. In addition, test results indicated that the void ratio of coal mine spoil approached values of 0.3 to 0.35, corresponding to dry densities of between 1.95 and 2.1 t/m 3 , at 10 MPa applied stress, regardless of moisture state, maximum particle size, scalping method and magnitude of initial loading.As part of the research, a degradation test method was deve...

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Estimating hydrocompression potential of mine spoils from a site in eastern Kentucky using dry unit weight and moisture content

Cited by 6 publications

References 3 publications

A New Laboratory Model of a Slaking Chamber to Predict the Stability of on-Site Coal Mine Spoils

A New Laboratory Model of a Slaking Chamber to Predict the Stability of on-Site Coal Mine Spoils

The Effect of Void Ratio, Moisture Content and Vertical Pressure on the Hydrocompression Settlement of Copper Mine Tailing

Bulking and Subsequent Self-Weight and Saturation Settlements, and Geotechnical Stability of High Coal Mine Spoil Piles

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