Geotechnical Characterisation of Oil Sand Tailings Beach Deposits in Flume Tests

  • Author / Creator
    Anglow Kouakou, William
  • In recent years, the oil sands industry has been investigating alternatives to the conventional tailings management practice to address the accumulation of large volumes of mature fine tailings (MFT) and abide by new government regulations in the province of Alberta. The main goals are to achieve a 50% total fines capture and a minimum undrained shear strength gain of 5 kPa in one year for the deposited material in the dedicated oil sand tailings disposal area (DDA). TOTAL E&P Canada Ltd. is performing beaching studies in test flumes using MFT based slurries with different sand to fines ratio (SFR) at the Saskatchewan Research Council (SRC) facility in Saskatoon, SK. This thesis presents the results of the field and laboratory investigations which were implemented to analyse the fines capture of the resulting flume deposits. The beach materials were essentially silty sands and captured 9% - 17% fines. Vertical sorting and the distribution of fines particle along the slope of the beach were also observed throughout the deposits. The amount of fines captured was function of the slope of the beach deposits. The flume deposit with lower slope (i.e., 0.5%) captured 17% of fines as compared to 9% for the deposit with the highest slope (i.e., 8%). Additionally, the fines content was observed to increase with increasing distance away from the discharge point towards the toe of the beach slope. The magnitudes of in-situ and laboratory hydraulic conductivities (ks) were in the range of 1×10-6 m/s - 1×10-8 m/s and varied with respect to the fines content distribution. In general, the magnitudes of the vertical and horizontal ks were close to each other. A comparison of results from particle size distribution (PSD), soil water characteristic curves (SWCC) and associated drying curves indicated that the behaviour of the flume deposits was within the envelope of Devon silt (upper boundary) and typical tailings beach sand (lower boundary) samples. It was observed that the flume deposits exhibited both contractile and dilatant behaviours during direct shear tests with mean peak and residual friction angles of 38° and 33° respectively. Large strain consolidation tests highlighted the low compressibility of the flume deposits with about 1% change in void ratio with little change noted in k. Results of this study are of value for the oil sands industry for the management and modelling of the behaviour of deposited tailings.

  • Subjects / Keywords
  • Graduation date
    Fall 2014
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • 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.