Roadway Stability Monitoring System

This report describes the outcomes of a project that focussed on the development and trialling of a unique radar sensing technology to monitor roadway deformation in underground coal mines.

The development of technology capable of accurate and reliable monitoring of continuous regions of roadway roof or rib has been identified as a fundamentally important goal for the coal mining industry.  This project focussed on achieving the following objectives:

• Development of a sensing technology that can monitor continuous surfaces and detect millimetre deformations over extended time periods;
• Construction of a suitable test facility that can provide a reasonable facsimile of the mine roadway environment and allow simulation of deformation phenomena;
• Commissioning and testing of the sensor technology, first in the test facility, and ultimately in an underground roadway environment.

These project objectives were successfully achieved. The project saw the development of two distinct prototype radar sensors, together with the construction of a sophisticated test environment that could simulate the structural deformation encountered in roadways. The prototype radar systems were used extensively in this “test tunnel” environment to validate their fundamental performance capabilities, both accuracy and precision (repeatability). Both radar units achieved the required level of performance in the test environment, demonstrating the ability to detect changes in the surface profile of the test tunnel of one millimetre or less.

The second radar prototype, a compact and portable unit, was then used for an underground trial at Anglo American's Moranbah North mine. A series of tests were performed during the trial, including identification of roadway features, verification of sensor stability, sensor movement detection and compensation, and finally change detection.

The sensor successfully completed these field trial outcomes:

• Roadway features, including an adjacent cut-through and reinforcement structures such as bolt plates, were able to be detected and identified;
• The processing software identified sensor motion between multiple scans, allowing compensation to be applied to ensure that actual roadway deformation can be detected;
• The radar detected introduced change in the roof structure of approximately 1-2 mm.

The outcomes from this project demonstrate that the radar sensor developed is a valid and promising technology for the monitoring of underground roadway surface deformation. The next phase of research will apply these outcomes to extensive underground testing in two modes: wide area surveys of existing gateroads, and continuous monitoring in the immediate vicinity of mining.