Numerical Simulation Of Water Flow Through Unsaturated Soil In Vertical And Inclined Layered Systems

• Author / Creator

  Rodriguez, Jorge L

• In past decades, there were discussions explaining the mechanisms and factors that influence water flow through soil in unsaturated conditions. This phenomenon is of major importance to the mining industry as water is one of the trigger mechanisms for Acid Rock Generation (ARD) generation. In 1999, Newman evaluated water flow in unsaturated conditions for two column experiments using a vertical layer system of sandy materials and waste rock from the Golden Sunlight mine. Later in 2009, Andrina analyzed water flow using waste rock from the Grasberg Mine in three Meso-scale experiments to understand flow mechanisms for incline layers of waste rock. The current study focuses on modeling the two column experiments by Newman and the three Meso-scale panels by Andrina to analyze the mechanisms controlling water flow in unsaturated soils. Additionally, one of the models is evaluated under three additional materials to compare the effect of different hydraulic properties in an inclined layering system. With finite element methods, the experiments are modeled and calculated under equal boundary conditions. The use of climate boundaries recreates the precipitation flux and head pressure boundary to generate the suction from the discharge points. The models are run using SvFlux software, which runs an automatic mesh refinement algorithm and solves the Partial Differential Equations (PDEs) using FlexPDE. The models are validated based on the correlation of the discharge volume from each experiment. The results from the models describe the profile changes of head pressure (hp), flux, flow paths, and matric suction to describe the mechanism of flow in the unsaturated conditions. The validation of the models was achieved through back analyzing the different tests in the experiments, due to the low correlation of the model using the laboratory properties and the experimental results. The back analysis of the material is focused on the air entry value, and the saturated hydraulic conductivity as a means to change the unsaturated flow. The result from the research displays similarities and disagreements between the models and experiments. The models showed that the measured discharge from a particular material does not represent the preferential flow path of water, as a small gradient in the pressure distribution can generate breakthrough at the base of the system.

• Subjects / Keywords

  • Numerical Seepage
  • Waste Rock
  • Unsaturated Flow
  • Infiltration
  • Calibration
  • Modelling
  • Meso Scale Laboratory Testing

• Graduation date

  Spring 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3DR2PF20

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.