Abstract
The construction method used to build waste rock piles influences their internal structure. Commonly used methods typically lead to the creation of compacted material layers within otherwise loose, coarse-grained waste rock. These dense layers, which typically have a finer grain size, affect the movement and distribution of water inside the pile. Long-term numerical simulations of unsaturated flow in a large pile were conducted to investigate the effect of such layers. The simulations led to various observations that provide a better understanding of the hydrogeological behaviour of the modeled pile (based on an actual case). The results show how water distribution and seepage within the pile are influenced by the presence of these layers. Other factors, including the magnitude of precipitation (or recharge) and pile size, were also investigated. This article presents the main results of the simulations, with some comments on their practical implications for pile design.
Zusammenfassung
Die während des Aufbaus von Abraumhalden gewählte Schüttungsmethode hat Auswirkungen auf die interne Haldenstruktur. Übliche Schüttungsmethoden führen zur Ausbildung von kompaktierten Lagen innerhalb von locker gelagertem grobkörnigem Abraum. Die dichter gepackten Lagen sind normalerweise feinkörnig aufgebaut und beeinflussen die Sickerwasserbewegung und –verteilung innerhalb der Halde. Durch eine langzeitliche numerische Modellierung des ungesättigten Wassersflusses innerhalb von großen Abraumhalden (mit Bezug zu einem aktuellen Fallbeispiel) werden die Auswirkungen solcher verdichteten Lagen untersucht. Diese Modellierungen führen zu einer Vielzahl von Schlussfolgerungen, mit denen das hydrogeologische Regime innerhalb der untersuchten Halde besser beschrieben werden kann. Die Ergebnisse zeigen, wie die Wasserverteilung und die Sickerwasserbewegung innerhalb der Halde durch die Ausbildung verdichteter Lagen beeinflusst wird Andere Faktoren, wie z. B. die Niederschlagsmenge (und –neubildung) sowie die Haldengröße werden ebenfalls untersucht. In diesem Artikel werden die wesentlichen Ergebnisse der Modellierung aufgezeigt sowie Hinweise zur praktischen Umsetzung beim Haldenaufbau angegeben.
Resumen
El método de construcción utilizado para construir las pilas de residuos de roca influye en sus estructuras internas. Los métodos comúnmente usados implican la creación de capas de material compacto dentro de otras capas menos compactas de residuo de roca de grano grueso. Dichas capas densas que usualmente tienen un tamaño de grano más fino, afectan el movimiento y la distribución de agua dentro de la pila. Las simulaciones numéricas de flujo insaturado en una pila de gran tamaño han sido realizadas para investigar el efecto de tales capas. Las simulaciones condujeron a numerosas observaciones que proporcionan una mejor comprensión del comportamiento hidrogeológico de la pila modelada (basado sobre un caso real). Los resultados muestran que la distribución de agua y la filtración dentro de la pila están influidas por la presencia de estas capas. También fueron investigados otros factores, incluyendo la magnitud de precipitación (o recarga) y el tamaño de la pila. Este artículo presenta los principales resultados de las simulaciones con algunos comentarios sobre las implicancias prácticas para el diseño de pilas.
抽象
废石堆的堆建方式影响着它的内部结构。普通堆积方法常常在松散、粗粒的废石中形成夯实的致密层。致密层以细粒结构为特征,并影响着废石堆内部水分的运移和分布。本文通过大型废石堆中非饱和水流的长时段数值模拟研究了致密层的水文地质作用。该数值模拟使我们能够深入理解废石堆模型(基于实际废石堆建立)水文地质学特征。数值模拟结果展示了致密材料层如何影响废石堆中水分分布和渗流过程。同时,模拟研究了降水量(补给)和废石堆规模的影响。文章根据模拟结果提出了废石堆设计的实用意见。
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Acknowledgments
The authors received financial support from the Industrial NSERC Polytechnique-UQAT Chair on Environment and Mine Wastes Management and from the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST). This work continues as part of the research program of the newly created Research Institute on Mines and the Environment (RIME UQAT-Polytechnique).
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10230_2013_251_MOESM2_ESM.pdf
Table 4 (supplemental file): Relative error (%) of the water mass balance for all simulations (S1 to S11) at different times (PDF 5 kb)
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Figure II (supplemental file): Water retention curves and hydrulic conductivity functions for the sandy (SBL), silty (STL), and gravelly (GRV) materials; the k values are expressed in cm/s. (PDF 14 kb)
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Figure III (supplemental file): Contours of (A) the volumetric water contents and (B) velocity, cm/hr, for simulation S3 at the end of December of the 10th year; one sand layer is added on top of the pile (PDF 1,398 kb)
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Figure IV (supplemental file): Contours of (A) the volumetric water contents and (B) velocity, cm/hr, for simulation S5 at the end of December of the 10th year; four sand layers are added on top and inside the pile (PDF 2,447 kb)
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Figure V (supplemental file): Contours of (A) the volumetric water contents and (B) velocity, cm/hr, for simulation S9 at the end of December of the 10th year; the two silt layers added on top and at mid-height of the pile and inclined at 10 % (PDF 946 kb)
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Dawood, I., Aubertin, M. Effect of Dense Material Layers on Unsaturated Water Flow Inside a Large Waste Rock Pile: A Numerical Investigation. Mine Water Environ 33, 24–38 (2014). https://doi.org/10.1007/s10230-013-0251-7
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DOI: https://doi.org/10.1007/s10230-013-0251-7