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" Effects of Transient Hydro-Mechanical Cemented Paste Tailings Properties on One-Dimensional Deposition Behaviour "
Shahsavari Goughari, Mohammad
Grabinsky, Murray
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Latin Dissertation
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English
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| Record Number
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1055460
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TL54577
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Shahsavari Goughari, Mohammad
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| Title & Author
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Effects of Transient Hydro-Mechanical Cemented Paste Tailings Properties on One-Dimensional Deposition Behaviour\ Shahsavari Goughari, MohammadGrabinsky, Murray
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| College
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University of Toronto (Canada)
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| Date
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2020
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| Degree
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Ph.D.
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2020
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| Note
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176 p.
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| Abstract
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When underground mining voids are filled with Cemented Paste Backfill (CPB) a dynamic interaction occurs between the hydrating CPB's engineering properties (hydraulic conductivity, stiffness and strength) and the fill rise rate, drainage conditions, and underground atmospheric conditions. These interactions are particularly important in the first 24 hours after a fill layer's placement in order to support continuous filling. Unfortunately, most previous studies started taking measurements at one day or more, missing this critical initial period. The work presented in this thesis obtains representative material properties at curing times as soon as 30 minutes. Four stages of hydraulic conductivity evolution are linked to corresponding stages of binder hydration at times from 30 minutes to 5 days, and it is shown conventional measurement methods could under-estimate initial hydraulic conductivity by an order of magnitude. Consolidation tests with virtually continuous loading rates simulated effective stress development onsets between 4 and 48 hours, at rates between 5 and 20 kPa/hr and final level of 400 kPa. In virtually continuous loading it is impossible to deconvolve the parameters controlling the ultimately achieved void ratio and stiffness, but a graphical technique is developed to aid preliminary design and determine likely void ratios that should be used in other laboratory tests for engineering properties. The hydraulic conductivity and consolidation element test results are then used to interpret results from four mesoscale laboratory experiments that simulate continuous backfilling. These tests demonstrate the importance of properly simulating the underground atmospheric conditions, and in placing the fill in the most continuous manner possible. For placement conditions that most closely simulate the actual placement conditions at the studied mine, it is found that virtually no self-weight consolidation occurs and thus the void ratios in the field and in the meso-scale experiments are essentially identical. Therefore, the effective stress path realized in the field will not lead to significant self-weight consolidation and the attendant strength gains that might otherwise occur.
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Civil engineering
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Environmental engineering
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Mining
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Grabinsky, Murray
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University of Toronto (Canada)
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