Innovative Digital Instruments for Geotechnical Monitoring Systems

Mining Rocks! CIM Toronto 2005
Abstract Historical case studies will be reviewed which demonstrate how conventional analog geotechnical instrumentation has improved both the safety aspects and overall efficiency of mining excavations. However, the limitations of the analog technology deployed in these projects - which include (i) high purchase prices (ii) suspect reliability, (iii) complex interpretation procedures, and (iii) high priced data management tools – will be exposed.

Today, significantly more cost-effective geotechnical instruments can be built using digital (as opposed to analog) technology. Furthermore deployment of these instruments provides an opportunity to directly leverage the data communications infrastructure which exists at many underground mine-sites. The new generation of digital instruments have embedded FLASH microcontrollers that provide highly accurate and fully compensated digital data directly in “real world units” (mm of displacement, tonnes of load etc.). This digital data can be transmitted across existing wireless communication networks, collected directly using IrDA(infra-red) enabled PDA devices and low-cost (costing 80% less than analog alternatives) data-loggers, or interfaced with PLC’s hanging off the mine-site communication system. Thereafter the data can be interpreted directly and stored directly into a PC-based Data-Storage application. Based on a comparison between trends in the stored data and user-defined thresholds, e-mail alerts to engineers, supervisors, or consultants, can be initiated, with the relevant data attached in XML format.

The paper will present examples of innovative digital geotechnical instruments including GMMs (Ground Movement Monitors), borehole extensometers, reusable borehole extensometers, inclinometers, strain gauges, and thermo-strings. Strategies for implementing these sensors into a digital monitoring network will be presented.
The reduced cost of the new technology combined with the convenience with which the information generated can be gathered, interpreted and distributed, empowers engineers, managers and consultants to make faster and more informed ground control decisions that result from the challenges of narrow vein mining.

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