Open Collections

Establishing a Site-Specific Standard of Practice for Field Vane Shear Testing in Mine Tailings

Tailings and Mine Waste Conference (2023 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

The field vane shear test (FVT) provides the only direct measurement of in-situ yield and residual undrained shear strength and is widely used in geotechnical practice. However, use of this test in mine tailings requires modifications from the ASTM standard to achieve and maintain undrained conditions. This paper advances research presented in recent publications that identified concerns with the accuracy of data obtained in mine tailings using the ASTM standard, as well as those introducing high-speed FVT equipment and modified procedures for mine tailings applications. Herein, the authors present the results and interpretation of a field investigation program commissioned by a confidential mining client across multiple tailings storage facilities (TSFs). The investigation used these modified procedures and high-speed FVT equipment with the objective of mitigating risk associated with the uncertainty of whether FVT results used for selection of design parameters were in an undrained condition. To this end, a series of FVTs were performed at the same depths in adjacent soundings using a range of vane rotation rates for evaluation of both drainage and viscous effects on the measured yield and residual undrained shear strength. Companion cone penetration test (CPT) soundings with pore water pressure dissipation (PPD) tests were also conducted to support the characterization and interpretation. Results from this program demonstrate how the client, in a practical manner, was able to validate their standard of practice for high-speed FVT and determine optimal vane rotation rates that achieve undrained conditions while avoiding viscous effects for the various mine tailings across their portfolio of TSFs. For the mining industry, this provides a model for implementation of similar investigation programs at other TSFs to gain site-specific knowledge of vane rotation rate effects on the measured undrained shear strength for respective mine tailings, as well as a basis and directive for development of modified standards for mine tailings applications superseding the existing ASTM standard.

Text

2023-12-08

Attribution-NonCommercialNoDerivatives 4.0 International

http://hdl.handle.net/2429/86794

Unreviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/