REAL-TIME MONITORING OF AN ACTIVE LANDSLIDE IN A COAL MINE USING GPS, PORE PRESSURE AND INCLINOMETERS

After several unseasonably heavy rainstorms, a 260 acre landslide occurred at Trapper Coal Mine in northwest Colorado. Fortunately, the area was evacuated prior to the slide and no one was injured. In areas, the slide displaced ground more than 400 feet.

Applied Geomechanics designed an instrumentation array consisting of 1) GPS (Global Positioning System)—to monitor surface displacement in three dimensions; 2) In-Place Inclinometers—to measure subsurface rotation in zones prone to sliding; and 3) Vibrating Wire Piezometers—to measure subsurface pore pressure. All data is radioed to the main Trapper office and then fed, via the Internet, to a secure data server where it is processed and archived. The sensors monitor surface and subsurface changes and help the Trapper Mine staff identify slide precursors and evacuate the area appropriately.

Atlas is Applied Geomechanics’s monitoring software that runs on the Applied Geomechanics Data Center server. Atlas Monitoring Software is specially designed to process and distribute data collected from geotechnical sensors and users can access Atlas through the standard web browser. With the exception of GPS data, which is more thoroughly processed by 3D Tracker, all imported data is processed by Atlas as it is imported. This allows Atlas to scan for alarm conditions

Users can set several tiers of alarms with notification to different groups. If a sensor goes into an alarm condition, a Trapper specified group is notified by e-mail and text message. Some alarm conditions send a message to the monitoring stations and trigger the audible sirens and strobe lights notifying miners to evacuate the area immediately.

Conclusion

Applied Geomechanics designed an instrumentation system for a large, active landslide in Trapper Coal Mine. Three GPS sites measures three dimensional surface movement. GPS processing software help achieve mm accuracy. Four subsurface arrays measure tilt and pore pressure with inclinometers and piezometers. The subsurface stations share power and communication systems. Atlas, Applied Geomechanics’s web-based data monitoring software brings these three monitoring technologies together. Trapper engineers can configure plots to visualize their data and set alarms to help keep mining personal safe.