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Development of a tailings simulation model using System Dynamics

  • Author / Creator
    Zheng, Xiaochuan
  • This thesis aims to demonstrate the feasibility of using System Dynamics (SD) techniques to develop a transparent, open-source and reproducible model capable of simulating long-term soil water dynamics in a tailings-cap system subject to upward flux from a consolidating tailings substrate. The developed model, which consists of a consolidation sub-model and an un-saturated flow sub-model, explores various feedback mechanisms in the self-weight consolidation process and unsaturated soil water movement under climatic influence. The tailings simulation model uses Causal Loop Diagramming (CLD) techniques to identify key feedback structures, promote system thinking and facilitate shared understanding of the inter-related behaviour between the reclamation cap and the tailings substrate.The model is implemented in the GoldSim simulation environment. The consolidation sub-model uses an explicit finite difference method to calculate the void ratio at each time step. Through various validation cases, the consolidation sub-model demonstrates its capability in carrying out both deterministic and stochastic simulations. The unsaturated flow sub-model is based on a previously developed infiltration-drainage model. This research improves the original model by adding capabilities of handling dynamic boundary conditions and inter-layer overflow mechanisms. Additional validation cases are conducted to build confidence in the modified model.The integrated model simulated a case study involving a 3 m thick coarse sand tailings (CST) cap on top of a 50 m thick thickened tailings (TT) deposit. Simulation results show that soil water dynamics in the CST cap is highly sensitive to the water release from the TT settlement. An increase in the initial solids contents of TT by 10% can delay the daylighting of the consolidation flux at the cap surface by one to two years. In order to prevent the daylighting of consolidation release water at the surface, the initial solids content of TT needs to be above 60%. The simulation also shows that the local behaviour of soil water storage in the CST cap is sensitive to changes in saturated hydraulic conductivity while the global behaviour is less sensitive to such changes.Supplemental material related to this thesis is available at https://era.library.ca/collections/7p88ck40x

  • Subjects / Keywords
  • Graduation date
    Spring 2019
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/r3-tbnn-0504
  • License
    Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.