Borehole Tomography and Surface 3D Radar for Coal Mine Subsidence Detection

 

James P. Conroy, M.S.

ENSCO, Inc., 5400 Port Royal Road, Springfield, Virginia, USA
Email: conroy.jim@ensco.com

Erich D. Guy, Ph.D.

U.S. Army Corps of Engineers, 502 Eighth Street, Huntington, West Virginia, USA
Email: Erich.D.Guy@usace.army.mil

ABSTRACT

Experimental cross-hole and surface-penetrating radar surveys were conducted along a section of highway that had collapsed into underground coal mine workings. The cross-hole radar method provided information about bedrock and overburden conditions at depths not attainable using surface radar, while the surface radar enabled a detailed analysis of the roadway conditions. Through coincident analyses of borehole tomograms and surface three-dimensional plots, additional locations along the highway where mine-related disruption has occurred, and where a relatively high potential for future collapse exists, were detected. The results of this study demonstrate the applicability of radar methods to mine-related subsidence problems, and show that a more complete characterization can be achieved by employing both borehole and surface radar methods

KEYWORDS: GPR, radar, 3D, borehole, tomography, coal, subsidence, mining, geophysics

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