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Geotechnical Engineering


Geophysical Technologies for Detecting Underground Coal Mine Voids:
An Interactive Forum

Advanced Electromagnetic Wave Technologies for the Detection of Abandoned Mine Entries and Delineation of Barrier Pillars

Firm/Organization: Stolar Horizon, Inc.
Phone: (505) 445-3607
Fax: (505) 445-9659
Mailing Address: P.O. Box 428
Raton, New Mexico 87730

Presenter: Syd S. Peng, Ph.D.
Firm/Organization: West Virginia University, Department of Mining Engineering
Phone: (304) 293-7680 ext 3301
Fax: (304) 293-5708
Mailing Address: P.O. Box 6070
Morgantown, West Virginia 26506-6070


The current high level of coal production is rapidly depleting easily minable coal reserves. Future mining will gradually concentrate in thinner, deeper, and geologically adverse coal seams. Some of the mining projects will be near old works where geophysical mapping methods will be applied separately or in conjunction with drilling techniques to delineate barrier pillars and detect voids ahead of mining machines. Several electromagnetic (EM) wave methods of detection and imaging of voids, impoundment leakage pathways, and geologic anomalies in coal beds have been investigated in recent years. Surface-based survey methods include magnetotelluric and local transmitters using low frequencies and radar at high frequencies. Both reflection and transmission instrumentation have been developed for surface, borehole, and in-mine applications.

This paper has been written for decision-makers in the coal mining industry who are concerned with the detection, confirmation, and mitigation of mining hazards in advance of mining. First, a practical insight into the science of EM wave energy travel in the coal bed has been prepared to give an understanding of EM wave interaction with voids, leakage pathways, oil/gas well casings, and geologic anomalies. Second, the interaction forms observables that are detected with specialized instrumentation. The surface-based instrumentation includes EM gradiometers and radar; in-mine and borehole instrumentation includes radar and the Radio Imaging Method (RIM). This paper also describes the development of radar for horizontal directional drills and cutting drums. Return to Forum Index Continue to Paper

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Updated: 04/07/2011

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