Underground » Strata Control and Windblasts
This project outlines the development of a cost effective, routine shear monitoring instrument for deployment in ungrouted boreholes. The system will be based on an existing MEMS (Micro Electrical Mechanical Systems) sensor from Holville that is certified (IECEx 12.0034X) intrinsically safe for use in Australian coal mines. A hand-held readout unit designed to be intrinsically safe (IS) has been developed as well as an IS approved two wire Holville roofAlert™ communication and logging system.
The SmartShear instrument has been developed to accurately measure shear movement at multiple horizons within a borehole. The instrument is designed to measure shear movement up to ten metres into an open borehole, sufficiently covering cable bolt lengths. The shear movement is measured on a two dimensional plane at 90 degrees to the installation of the instrument using a series of MEMS tiltmeter sensors. Continual change in shear direction and magnitude over time is measured once the shear locations are detected.
The SmartShear instrument consists of a series of jointed segments called bays. Attached to each bay length is a spring loaded plastic anchoring system that when activated, enables the bay length to centralise in the borehole, mechanically anchoring itself in position without the need for cement or resin. Each bay length contains one MEMS tiltmeter. A hand-held readout unit has been designed to be IS with the ability to download data either wired or wirelessly by the press of a button.
With the ability to measure the change in shear movement over time, the SmartShear has been designed to be integrated into mine sites Tigger Action Response Plan (TARP), allowing early remedial action to be taken to ensure roadway stability. Valuable information gained from the SmartShear system can then be used for future roadway and support designs. The SmartShear is designed to connect to the roofAlert system, a real time monitoring system that links up the SmartShear as well as other geotechnical instruments. The data is sent live to the control room, prompting actions that arise from pre-set triggers within the TARPS.