Piezometer–friction cone investigation at a tailings dam

Abstract

Static piezometer–friction cone tests were carried out at the tailings dam at Brenda Mines, Peachland, British Columbia to evaluate soil characteristics and seepage conditions in the dam. Several types of electric quasistatic cones were pushed to depths of 40–70 m at various locations in the dam and on the beach. The cones used included both the Fugro electric friction cone and piezometer cone, and a University of British Columbia designed piezometer–friction cone.Site conditions are described and typical cone logs of bearing, friction, friction ratio, and pore water pressure vs. depth are presented, interpreted, and discussed. The cone data is used to assess strength and relative density, and to assess gradational variations of the tailings and slimes on the beach, including the identification of ice inclusions.Measurements of equilibrium pore water pressures with depth at three locations on the beach allowed a clear picture to be developed of the pore pressure gradients within the dam. Other problems and experiences concerning quasistatic cone logging for a tailings dam are also discussed. Key words: in situ testing, static penetration testing, piezometer cone, tailings dam, tailings beach, seepage, strength, relative density, ice, pore pressures.