Advancing vane shear testing – development and first field application of a piezometer vane (VSTu)

January 7, 2026

This paper presents the development and initial field deployment of a prototype variable rate piezometer vane shear test device (VSTu or VR-VSTu) designed to measure porewater pressure (PWP) on the vane blade edge during insertion and shearing of soils or tailings in the field. The device was developed to address drainage uncertainties when conducting vane shear testing, in materials such as mine tailings, intermediate soils, and dredge materials. To ensure compatibility with existing VST results, the VSTu was designed to comply with standard vane dimensions, while integrating additional instrumentation. In addition to recording PWP and torque during shearing, the PWP response is recorded during insertion. Observations of induced pore pressure, or lack thereof, during vane insertion and shearing can provide insights into whether materials are undrained, partially drained, or freely draining. By integrating PWP measurement during shearing, the VSTu has the potential to offer insights into the brittleness, sensitivity, consolidation, and large strain behaviour. This paper presents results from the deployment of the VSTu at the East Kemptville tin tailings site in Nova Scotia, Canada. Field testing was conducted in both coarse and fine tailings, and results indicate the device can capture meaningful PWP responses during insertion and shearing, with implications for identifying drainage conditions and assessing undrained shear strength.

Byrne, YN., Greig, J., Small, A., DeJong, J. and Cator, K. 2025 " Advancing vane shear testing – development and first field application of a piezometer vane (VSTu),” in Proceedings of the LOM-MWT Conference 2025, July 29 – 30, 2025. Brisbane, Australia: Australian Institute of Mining and Metallurgy (AusIMM)