Vibrating Wire Piezometer Boreholes and The Importance of Validating their Installation
El idrysy, Houcyne; Sultanov, Lenar; Raynor, Mark
SRK Consulting (UK) Ltd, United Kingdom
The use of Vibrating Wire Piezometer (VWP) boreholes to collect pore water pressure data from ground formations has become a common practice in several fields, including the mining industry. The most common use of VWPs in mining projects is for monitoring pore pressure in the pit walls for slope stability analysis and optimisation. The principal advantage of VWPs resides in the ability of such installations to collect pore pressure information from various layers in the same borehole, and their relative ease of installation in narrow diameter geotechnical boreholes. However, calibration of the sensors and impervious grout seals between these are required for the installation to be reliable. Verification and validation of the VWP data during and after the installation is of paramount importance given the importance of the data to the slope design process. This paper will discuss VWP borehole installation and data analysis and provide examples where insufficient data collection at the installation stage could have resulted in significant errors in measured pore pressures. The paper will also discuss the range of hydrogeological settings where VWP’s are installed and highlight those settings where grouted-in VWP installations may not be appropriate.